WorldWideScience

Sample records for relay-assisted ofdma cellular

  1. Energy-efficient power control for OFDMA cellular networks

    KAUST Repository

    Sboui, Lokman

    2016-12-24

    In this paper, we study the energy efficiency (EE) of orthogonal frequency-division multiple access (OFDMA) cellular networks. Our objective is to present a power allocation scheme that maximizes the EE of downlink communications. We propose a novel explicit expression of the optimal power allocation to each subcarrier. We also present the power control when the transmit power is limited by power budget constraint or/and minimal rate constraint and we highlight the occurrence of some transmission outage events depending on the constraints\\' parameters. In the numerical results, we show that our proposed power control improves the EE especially at high power budget regime and low minimal rate regime. In addition, we show that having a higher number of subcarriers enhances the OFDMA EE.

  2. Channel Asymmetry in Cellular OFDMA-TDD Networks

    Directory of Open Access Journals (Sweden)

    Agyapong Patrick

    2008-01-01

    Full Text Available Abstract This paper studies time division duplex- (TDD- specific interference issues in orthogonal frequency division multiple access- (OFDMA- TDD cellular networks arising from various uplink (UL/downlink (DL traffic asymmetries, considering both line-of-sight (LOS and non-LOS (NLOS conditions among base stations (BSs. The study explores aspects both of channel allocation and user scheduling. In particular, a comparison is drawn between the fixed slot allocation (FSA technique and a dynamic channel allocation (DCA technique for different UL/DL loads. For the latter, random time slot opposing (RTSO is assumed due to its simplicity and its low signaling overhead. Both channel allocation techniques do not obviate the need for user scheduling algorithms, therefore, a greedy and a fair scheduling approach are applied to both the RTSO and the FSA. The systems are evaluated based on spectral efficiency, subcarrier utilization, and user outage. The results show that RTSO networks with DL-favored traffic asymmetries outperform FSA networks for all considered metrics and are robust to LOS between BSs. In addition, it is demonstrated that the greedy scheduling algorithm only offers a marginal increase in spectral efficiency as compared to the fair scheduling algorithm, while the latter exhibits up to 20% lower outage.

  3. A NEW DISCRETE HARTLEY TRANSFORM PRECODING BASED INTERLEAVED-OFDMA UPLINK SYSTEM WITH REDUCED PAPR FOR 4G CELLULAR NETWORKS

    Directory of Open Access Journals (Sweden)

    VARUN JEOTI

    2011-12-01

    Full Text Available High peak-to-average power ratio (PAPR reduction is one of the major challenges in orthogonal frequency division multiple access (OFDMA systems since last decades. High PAPR increases the complexity of analogue-to-digital (A/D and digital-to-analogue (D/A convertors and also reduces the efficiency of RF high-power-amplifier (HPA. In this paper, we present a new Discrete- Hartley transform (DHT precoding based interleaved-OFDMA uplink system for PAPR reduction in the upcoming 4G cellular networks. Extensive computer simulations have been performed to analyze the PAPR of the proposed system with root-raised-cosine (RRC pulse shaping. We also compare simulation results of the proposed system with the conventional interleaved-OFDMA uplink systems and the Walsh-Hadamard transform (WHT precoding based interleaved-OFDMA uplink systems. It is concluded from the computer simulations that the proposed system has low PAPR as compared to the conventional interleaved-OFDMA uplink systems and the WHT precoded interleaved-OFDMA uplink systems.

  4. Adaptive Subframe Partitioning and Efficient Packet Scheduling in OFDMA Cellular System with Fixed Decode-and-Forward Relays

    Science.gov (United States)

    Wang, Liping; Ji, Yusheng; Liu, Fuqiang

    The integration of multihop relays with orthogonal frequency-division multiple access (OFDMA) cellular infrastructures can meet the growing demands for better coverage and higher throughput. Resource allocation in the OFDMA two-hop relay system is more complex than that in the conventional single-hop OFDMA system. With time division between transmissions from the base station (BS) and those from relay stations (RSs), fixed partitioning of the BS subframe and RS subframes can not adapt to various traffic demands. Moreover, single-hop scheduling algorithms can not be used directly in the two-hop system. Therefore, we propose a semi-distributed algorithm called ASP to adjust the length of every subframe adaptively, and suggest two ways to extend single-hop scheduling algorithms into multihop scenarios: link-based and end-to-end approaches. Simulation results indicate that the ASP algorithm increases system utilization and fairness. The max carrier-to-interference ratio (Max C/I) and proportional fairness (PF) scheduling algorithms extended using the end-to-end approach obtain higher throughput than those using the link-based approach, but at the expense of more overhead for information exchange between the BS and RSs. The resource allocation scheme using ASP and end-to-end PF scheduling achieves a tradeoff between system throughput maximization and fairness.

  5. Generalized instantly decodable network coding for relay-assisted networks

    KAUST Repository

    Elmahdy, Adel M.; Sorour, Sameh; Seddik, Karim G.

    2013-01-01

    which employs generalized IDNC instead of strict IDNC previously proposed in the literature for the same relay-assisted topology. This use of generalized IDNC is supported by showing that it is a super-set of the strict IDNC scheme, and thus can generate

  6. Generalized instantly decodable network coding for relay-assisted networks

    KAUST Repository

    Elmahdy, Adel M.

    2013-09-01

    In this paper, we investigate the problem of minimizing the frame completion delay for Instantly Decodable Network Coding (IDNC) in relay-assisted wireless multicast networks. We first propose a packet recovery algorithm in the single relay topology which employs generalized IDNC instead of strict IDNC previously proposed in the literature for the same relay-assisted topology. This use of generalized IDNC is supported by showing that it is a super-set of the strict IDNC scheme, and thus can generate coding combinations that are at least as efficient as strict IDNC in reducing the average completion delay. We then extend our study to the multiple relay topology and propose a joint generalized IDNC and relay selection algorithm. This proposed algorithm benefits from the reception diversity of the multiple relays to further reduce the average completion delay in the network. Simulation results show that our proposed solutions achieve much better performance compared to previous solutions in the literature. © 2013 IEEE.

  7. Mobile User Connectivity in Relay-Assisted Visible Light Communications

    Directory of Open Access Journals (Sweden)

    Petr Pešek

    2018-04-01

    Full Text Available In this paper, we investigate relay-assisted visible light communications (VLC where a mobile user acts as a relay and forwards data from a transmitter to the end mobile user. We analyse the utilization of the amplify-and-forward (AF and decode-and-forward (DF relaying schemes. The focus of the paper is on analysis of the behavior of the mobile user acting as a relay while considering a realistic locations of the receivers and transmitters on a standard mobile phone, more specifically with two photodetectors on both sides of a mobile phone and a transmitting LED array located upright. We also investigate dependency of the bit error rate (BER performance on the azimuth and elevation angles of the mobile relay device within a typical office environment. We provide a new analytical description of BER for AF and DF-based relays in VLC. In addition we compare AF and DF-based systems and show that DF offers a marginal improvement in the coverage area with a BER < 10–3 and a data rate of 100 Mb/s. Numerical results also illustrate that relay-based systems offer a significant improvement in terms of the coverage compared to direct non-line of sight VLC links.

  8. Multi-diversity combining and selection for relay-assisted mixed RF/FSO system

    Science.gov (United States)

    Chen, Li; Wang, Weidong

    2017-12-01

    We propose and analyze multi-diversity combining and selection to enhance the performance of relay-assisted mixed radio frequency/free-space optics (RF/FSO) system. We focus on a practical scenario for cellular network where a single-antenna source is communicating to a multi-apertures destination through a relay equipped with multiple receive antennas and multiple transmit apertures. The RF single input multiple output (SIMO) links employ either maximal-ratio combining (MRC) or receive antenna selection (RAS), and the FSO multiple input multiple output (MIMO) links adopt either repetition coding (RC) or transmit laser selection (TLS). The performance is evaluated via an outage probability analysis over Rayleigh fading RF links and Gamma-Gamma atmospheric turbulence FSO links with pointing errors where channel state information (CSI) assisted amplify-and-forward (AF) scheme is considered. Asymptotic closed-form expressions at high signal-to-noise ratio (SNR) are also derived. Coding gain and diversity order for different combining and selection schemes are further discussed. Numerical results are provided to verify and illustrate the analytical results.

  9. Adaptive resource allocation scheme using sliding window subchannel gain computation: context of OFDMA wireless mobiles systems

    International Nuclear Information System (INIS)

    Khelifa, F.; Samet, A.; Ben Hassen, W.; Afif, M.

    2011-01-01

    Multiuser diversity combined with Orthogonal Frequency Division Multiple Access (OFDMA) are a promising technique for achieving high downlink capacities in new generation of cellular and wireless network systems. The total capacity of OFDMA based-system is maximized when each subchannel is assigned to the mobile station with the best channel to noise ratio for that subchannel with power is uniformly distributed between all subchannels. A contiguous method for subchannel construction is adopted in IEEE 802.16 m standard in order to reduce OFDMA system complexity. In this context, new subchannel gain computation method, can contribute, jointly with optimal assignment subchannel to maximize total system capacity. In this paper, two new methods have been proposed in order to achieve a better trade-off between fairness and efficiency use of resources. Numerical results show that proposed algorithms provide low complexity, higher total system capacity and fairness among users compared to others recent methods.

  10. Individual Channel Estimation in a Diamond Relay Network Using Relay-Assisted Training

    Directory of Open Access Journals (Sweden)

    Xianwen He

    2017-01-01

    Full Text Available We consider the training design and channel estimation in the amplify-and-forward (AF diamond relay network. Our strategy is to transmit the source training in time-multiplexing (TM mode while each relay node superimposes its own relay training over the amplified received data signal without bandwidth expansion. The principal challenge is to obtain accurate channel state information (CSI of second-hop link due to the multiaccess interference (MAI and cooperative data interference (CDI. To maintain the orthogonality between data and training, a modified relay-assisted training scheme is proposed to migrate the CDI, where some of the cooperative data at the relay are discarded to accommodate relay training. Meanwhile, a couple of optimal zero-correlation zone (ZCZ relay-assisted sequences are designed to avoid MAI. At the destination node, the received signals from the two relay nodes are combined to achieve spatial diversity and enhanced data reliability. The simulation results are presented to validate the performance of the proposed schemes.

  11. A generic interference model for uplink OFDMA networks with fractional frequency reuse

    KAUST Repository

    Tabassum, Hina

    2014-03-01

    Fractional frequency reuse (FFR) has emerged as a viable solution to coordinate and mitigate cochannel interference (CCI) in orthogonal frequency-division multiple-access (OFDMA)-based wireless cellular networks. The incurred CCI in cellular networks with FFR is highly uncertain and varies as a function of various design parameters that include the user scheduling schemes, the transmit power distribution among multiple allocated subcarriers, the partitioning of the cellular region into cell-edge and cell-center zones, the allocation of spectrum within each zone, and the channel reuse factors. To this end, this paper derives a generic analytical model for uplink CCI in multicarrier OFDMA networks with FFR. The derived expressions capture several network design parameters and are applicable to any composite fading-channel models. The accuracy of the derivations is verified via Monte Carlo simulations. Moreover, their usefulness is demonstrated by obtaining closed-form expressions for the Rayleigh fading-channel model and by evaluating important network performance metrics such as ergodic capacity. Numerical results provide useful system design guidelines and highlight the trade-offs associated with the deployment of FFR schemes in OFDMA-based networks. © 2013 IEEE.

  12. A generic interference model for uplink OFDMA networks with fractional frequency reuse

    KAUST Repository

    Tabassum, Hina; Dawy, Zaher; Alouini, Mohamed-Slim; Yilmaz, Ferkan

    2014-01-01

    Fractional frequency reuse (FFR) has emerged as a viable solution to coordinate and mitigate cochannel interference (CCI) in orthogonal frequency-division multiple-access (OFDMA)-based wireless cellular networks. The incurred CCI in cellular networks with FFR is highly uncertain and varies as a function of various design parameters that include the user scheduling schemes, the transmit power distribution among multiple allocated subcarriers, the partitioning of the cellular region into cell-edge and cell-center zones, the allocation of spectrum within each zone, and the channel reuse factors. To this end, this paper derives a generic analytical model for uplink CCI in multicarrier OFDMA networks with FFR. The derived expressions capture several network design parameters and are applicable to any composite fading-channel models. The accuracy of the derivations is verified via Monte Carlo simulations. Moreover, their usefulness is demonstrated by obtaining closed-form expressions for the Rayleigh fading-channel model and by evaluating important network performance metrics such as ergodic capacity. Numerical results provide useful system design guidelines and highlight the trade-offs associated with the deployment of FFR schemes in OFDMA-based networks. © 2013 IEEE.

  13. A Precoded OFDMA System with User Cooperation

    NARCIS (Netherlands)

    Yu, Yao; Yatawatta, Sarod; Petropulu, Athina P.

    2010-01-01

    A new cooperative scheme for a two-user orthogonal frequency division multiple access (OFDMA) uplink communication scenario is proposed. Each user is equipped with one transmit/receive antenna. Before transmission, inter-block linear precoding is introduced to pairs of blocks. The cooperative

  14. On the throughput of a relay-assisted cognitive radio MIMO channel with space alignment

    KAUST Repository

    Sboui, Lokman; Ghazzai, Hakim; Rezki, Zouheir; Alouini, Mohamed-Slim

    2014-01-01

    We study the achievable rate of a multiple antenna relay-assisted cognitive radio system where a secondary user (SU) aims to communicate instantaneously with the primary user (PU). A special linear precoding scheme is proposed to enable the SU to take advantage of the primary eigenmodes. The used eigenmodes are subject to an interference constraint fixed beforehand by the primary transmitter. Due to the absence of a direct link, both users exploit an amplify-and-forward relay to accomplish their transmissions to a common receiver. After decoding the PU signal, the receiver employs a successive interference cancellation (SIC) to estimate the secondary message. We derive the optimal power allocation that maximizes the achievable rate of the SU respecting interference, peak and relay power constraints. Furthermore, we analyze the SIC detection accuracy on the PU throughput. Numerical results highlight the cognitive rate gain achieved by our proposed scheme without harming the primary rate. In addition, we show that the relay has an important role in increasing or decreasing PU and SU rates especially when varying its power and/or its amplifying gain. © 2014 IFIP.

  15. On the throughput of a relay-assisted cognitive radio MIMO channel with space alignment

    KAUST Repository

    Sboui, Lokman

    2014-05-01

    We study the achievable rate of a multiple antenna relay-assisted cognitive radio system where a secondary user (SU) aims to communicate instantaneously with the primary user (PU). A special linear precoding scheme is proposed to enable the SU to take advantage of the primary eigenmodes. The used eigenmodes are subject to an interference constraint fixed beforehand by the primary transmitter. Due to the absence of a direct link, both users exploit an amplify-and-forward relay to accomplish their transmissions to a common receiver. After decoding the PU signal, the receiver employs a successive interference cancellation (SIC) to estimate the secondary message. We derive the optimal power allocation that maximizes the achievable rate of the SU respecting interference, peak and relay power constraints. Furthermore, we analyze the SIC detection accuracy on the PU throughput. Numerical results highlight the cognitive rate gain achieved by our proposed scheme without harming the primary rate. In addition, we show that the relay has an important role in increasing or decreasing PU and SU rates especially when varying its power and/or its amplifying gain. © 2014 IFIP.

  16. Rate Adaptive OFDMA Communication Systems

    International Nuclear Information System (INIS)

    Abdelhakim, M.M.M.

    2009-01-01

    Due to the varying nature of the wireless channels, adapting the transmission parameters, such as code rate, modulation order and power, in response to the channel variations provides a significant improvement in the system performance. In the OFDM systems, Per-Frame adaptation (PFA) can be employed where the transmission variables are fixed over a given frame and may change from one frame to the other. Subband (tile) loading offers more degrees of adaptation such that each group of carriers (subband) uses the same transmission parameters and different subbands may use different parameters. Changing the code rate for each tile in the same frame, results in transmitting multiple codewords (MCWs) for a single frame. In this thesis a scheme is proposed for adaptively changing the code rate of coded OFDMA systems via changing the puncturing rate within a single codeword (SCW). In the proposed structure, the data is encoded with the lowest available code rate then it is divided among the different tiles where it is punctured adaptively based on some measure of the channel quality for each tile. The proposed scheme is compared against using multiple codewords (MCWs) where the different code rates for the tiles are obtained using separate encoding processes. For bit interleaved coded modulation architecture two novel interleaving methods are proposed, namely the puncturing dependant interleaver (PDI) and interleaved puncturing (IntP), which provide larger interleaving depth. In the PDI method the coded bits with the same rate over different tiles are grouped for interleaving. In IntP structure the interleaving is performed prior to puncturing. The performance of the adaptive puncturing technique is investigated under constant bit rate constraint and variable bit rate. Two different adaptive modulation and coding (AMC) selection methods are examined for variable bit rate adaptive system. The first is a recursive scheme that operates directly on the SNR whereas the second

  17. A new access scheme in OFDMA systems

    Institute of Scientific and Technical Information of China (English)

    GU Xue-lin; YAN Wei; TIAN Hui; ZHANG Ping

    2006-01-01

    This article presents a dynamic random access scheme for orthogonal frequency division multiple access (OFDMA) systems. The key features of the proposed scheme are:it is a combination of both the distributed and the centralized schemes, it can accommodate several delay sensitivity classes,and it can adjust the number of random access channels in a media access control (MAC) frame and the access probability according to the outcome of Mobile Terminals access attempts in previous MAC frames. For floating populated packet-based networks, the proposed scheme possibly leads to high average user satisfaction.

  18. Comparison of Strategies for Signaling of Scheduling Assignments in Wireless OFDMA

    OpenAIRE

    Moosavi, Reza; Eriksson, Jonas; Larsson, Erik G.; Wiberg, Niclas; Frenger, Pål; Gunnarsson, Fredrik

    2010-01-01

    This paper considers transmission of scheduling information in  OFDMA-based cellular communication systems such as 3GPP long-term  evolution (LTE). These systems provide efficient usage of radio  resources by allowing users to be scheduled dynamically in both  frequency and time. This requires considerable amounts of scheduling  information to be sent to the users.  The paper compares two basic transmission strategies: transmitting a  separate scheduling message to each user versus broadcasti...

  19. Receiver based PAPR reduction in OFDMA

    KAUST Repository

    Ali, Anum Z.; Al-Zahrani, Ali Y.; Al-Naffouri, Tareq Y.; Naguib, Ayman F.

    2014-01-01

    High peak-to-average power ratio is one of the major drawbacks of orthogonal frequency division multiplexing (OFDM). Clipping is the simplest peak reduction scheme, however, it requires clipping mitigation at the receiver. Recently compressed sensing has been used for clipping mitigation (by exploiting the sparse nature of clipping signal). However, clipping estimation in multi-user scenario (i.e., OFDMA) is not straightforward as clipping distortions overlap in frequency domain and one cannot distinguish between distortions from different users. In this work, a collaborative clipping removal strategy is proposed based on joint estimation of the clipping distortions from all users. Further, an effective data aided channel estimation strategy for clipped OFDM is also outlined. Simulation results are presented to justify the effectiveness of the proposed schemes. © 2014 IEEE.

  20. Receiver based PAPR reduction in OFDMA

    KAUST Repository

    Ali, Anum Z.

    2014-05-01

    High peak-to-average power ratio is one of the major drawbacks of orthogonal frequency division multiplexing (OFDM). Clipping is the simplest peak reduction scheme, however, it requires clipping mitigation at the receiver. Recently compressed sensing has been used for clipping mitigation (by exploiting the sparse nature of clipping signal). However, clipping estimation in multi-user scenario (i.e., OFDMA) is not straightforward as clipping distortions overlap in frequency domain and one cannot distinguish between distortions from different users. In this work, a collaborative clipping removal strategy is proposed based on joint estimation of the clipping distortions from all users. Further, an effective data aided channel estimation strategy for clipped OFDM is also outlined. Simulation results are presented to justify the effectiveness of the proposed schemes. © 2014 IEEE.

  1. Performance analysis of relay-assisted all-optical FSO networks over strong atmospheric turbulence channels with pointing errors

    KAUST Repository

    Yang, Liang

    2014-12-01

    In this study, we consider a relay-assisted free-space optical communication scheme over strong atmospheric turbulence channels with misalignment-induced pointing errors. The links from the source to the destination are assumed to be all-optical links. Assuming a variable gain relay with amplify-and-forward protocol, the electrical signal at the source is forwarded to the destination with the help of this relay through all-optical links. More specifically, we first present a cumulative density function (CDF) analysis for the end-to-end signal-to-noise ratio. Based on this CDF, the outage probability, bit-error rate, and average capacity of our proposed system are derived. Results show that the system diversity order is related to the minimum value of the channel parameters.

  2. Contribution to Dynamic Spectrum Assignment in multicell OFDMA networks

    OpenAIRE

    Bernardo Alvarez, Francisco

    2010-01-01

    La próxima cuarta generación (4G) de redes de comunicaciones móviles celulares considera una interfaz radio basada en OFDMA (Orthogonal Frequency Division Multiple Access). Esta tecnología ofrece robustez a la propagación multicamino y diversidad en frecuencia gracias a la división del ancho de banda de operación en un conjunto de pequeños subcanales en frecuencia para así alcanzar un uso eficiente del espectro. Sin embargo, un importante desafío en una interfaz radio OFDMA es la manera en la...

  3. Synchronization for the uplink of OFDMA-based System

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong

    2008-01-01

    are designed for single-user system, and therefore are not able to correct multiple CFOs in the uplink. The aim of this thesis is to provide practical solutions  for the synchronization issues occurring in the uplink of the OFDMA-based broadband wireless systems.  Several data-aided CFO estimation algorithms...

  4. Communication and Jamming BDA of OFDMA Communication Systems Using the Software Defined Radio Platform WARP

    Science.gov (United States)

    2015-03-01

    COMMUNICATION AND JAMMING BDA OF OFDMA COMMUNICATION SYSTEMS USING THE SOFTWARE DEFINED RADIO PLATFORM WARP THESIS Kate J. Yaxley, FLTLT, Royal... BDA OF OFDMA COMMUNICATION SYSTEMS USING THE SOFTWARE DEFINED RADIO PLATFORM WARP THESIS Presented to the Faculty Department of Electrical and...COMMUNICATION AND JAMMING BDA OF OFDMA COMMUNICATION SYSTEMS USING THE SOFTWARE DEFINED RADIO PLATFORM WARP THESIS Kate J. Yaxley, B.E. (Elec) Hons Div II

  5. Energy-efficient power control for OFDMA cellular networks

    KAUST Repository

    Sboui, Lokman; Rezki, Zouheir; Alouini, Mohamed-Slim

    2016-01-01

    explicit expression of the optimal power allocation to each subcarrier. We also present the power control when the transmit power is limited by power budget constraint or/and minimal rate constraint and we highlight the occurrence of some transmission

  6. Optimal OFDMA Downlink Scheduling Under a Control Signaling Cost Constraint

    OpenAIRE

    Larsson, Erik G.

    2010-01-01

    This paper proposes a new algorithm for downlink scheduling in OFDMA systems. The method maximizes the throughput, taking into account the amount of signaling needed to transmit scheduling maps to the users. A combinatorial problem is formulated and solved via a dynamic programming approach reminiscent of the Viterbi algorithm. The total computational complexity of the algorithm is upper boundedby O(K^4N) where K is the number of users that are being considered for scheduling in a frame and N...

  7. Integrated Fractional Load and Packet Scheduling for OFDMA Systems

    DEFF Research Database (Denmark)

    Monghal, Guillaume Damien; Kumar, S.; Pedersen, Klaus I.

    2009-01-01

    This paper study the performance of an orthogonal frequency division multiple access (OFDMA) system under fractional load based in long term evolution (LTE) downlink. Fractional load is defined by a situation where only a fraction of the bandwidth is used for transmission due to lack of traffic....... This type of situation should result in a global increase of signal to interference and noise ratio (SINR) conditions in the network. We propose different methods integrating the transmission pattern selection to the packet scheduling functionality of the enode-B depending only on the channel quality...

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

    Directory of Open Access Journals (Sweden)

    Zhang Xing

    2009-01-01

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

  9. Analytical Evaluation of the Performance of Proportional Fair Scheduling in OFDMA-Based Wireless Systems

    Directory of Open Access Journals (Sweden)

    Mohamed H. Ahmed

    2012-01-01

    Full Text Available This paper provides an analytical evaluation of the performance of proportional fair (PF scheduling in Orthogonal Frequency-Division Multiple Access (OFDMA wireless systems. OFDMA represents a promising multiple access scheme for transmission over wireless channels, as it combines the orthogonal frequency division multiplexing (OFDM modulation and subcarrier allocation. On the other hand, the PF scheduling is an efficient resource allocation scheme with good fairness characteristics. Consequently, OFDMA with PF scheduling represents an attractive solution to deliver high data rate services to multiple users simultaneously with a high degree of fairness. We investigate a two-dimensional (time slot and frequency subcarrier PF scheduling algorithm for OFDMA systems and evaluate its performance analytically and by simulations. We derive approximate closed-form expressions for the average throughput, throughput fairness index, and packet delay. Computer simulations are used for verification. The analytical results agree well with the results from simulations, which show the good accuracy of the analytical expressions.

  10. An investigation of dynamic subcarrier allocation in MIMO–OFDMA systems

    OpenAIRE

    Peng, Y; Armour, SMD; McGeehan, JP

    2007-01-01

    In this paper, orthogonal frequency-division multiple-access (OFDMA) systems with dynamic deterministic (as opposed to pseudorandom) allocation of subcarriers to users to exploit multiuser diversity are investigated. Previously published work on dynamic multiuser subcarrrier allocation for OFDMA systems with single-input-single-output (SISO) channels are surveyed. A near-optimal low-complexity algorithm for SISO systems, which is structurally similar to the algorithm by Rhee and Cioffi, is ex...

  11. Blind Demodulation of Pass Band OFDMA Signals and Jamming Battle Damage Assessment Utilizing Link Adaptation

    Science.gov (United States)

    2014-03-27

    Access (OFDMA) signal so that jamming effectiveness can be assessed; referred to in this research as Battle Damage Assessment ( BDA ). The research extends...the 802.16 Wireless Metropolitan Area Network (MAN) OFDMA standard, and presents a novel method for performing BDA via observation of Sub Carrier (SC...interferer is also evaluated where the blind demodulator’s performance is degraded. BDA is achieved via observing SC LA modulation behavior of the

  12. Flexible proportional-rate scheduling for OFDMA system

    KAUST Repository

    Leith, Alex

    2013-10-01

    In this paper, we study the sum-rate maximization algorithms for downlink and uplink orthogonal frequency division multiple access (OFDMA) systems under proportional-rate constraint (PRC) and minimum-rate constraint. We develop a low-complexity weighted channel signal-to-noise ratio (w-SNR)-based ranking scheme for user selection on each subchannel in OFDMA combined with waterfilling (WF) power allocation. Both offline and online optimization algorithms are developed to optimize the SNR weight vector to maximize the sum rate while satisfying several constraints, such as PRC. The offline weight optimization technique relies on the analytical throughput results developed in this paper, and the online weight adaptation method tracks the user rates and meets the PRC using a subgradient search. Furthermore, we introduce a novel SNR operating region test to enhance the multiuser diversity gain and the sum rate. The proposed schemes have a low complexity, which is linear to the numbers of users and subchannels. Simulation results verify the accuracy of the developed analytical rates and fairness formulas, and show that the proposed w-SNR schemes can achieve higher sum rates than several benchmark schemes that provide the PRC with either short-term or long-term fairness. © 2013 IEEE. © 2013 ESO.

  13. Efficient Design of OFDMA-Based Programmable Wireless Radios

    Directory of Open Access Journals (Sweden)

    Shah SFA

    2008-01-01

    Full Text Available With the increasing demand for efficient spectrum management, programmable wireless radios can potentially play a key role in shaping our future spectrum use. In this paper, we consider the design of low-power programmable wireless radios based on orthogonal frequency division multiple access (OFDMA. To meet the demands of higher data rate communications, we split OFDMA symbols carrying multiuser data across several noncontiguous bands of available spectrum. To relax power consumption in analog-to-digital and digital-to-analog converters, we use a programmable narrowband RF front end comprising of programmable synthesizers and fixed low-pass filters. To perform digital baseband signal processing in an energy efficient manner, we propose efficient designs for the fast Fourier transform (FFT and inverse FFT (IFFT modules. Our designs of the FFT/IFFT modules reduce power consumption and chip area, and are capable of handling the dynamic nature of spectrum in programmable radios. To recover data that falls within the transition band of the filters, we propose a combiner similar to maximal ratio combiner. We also present the complete design of programmable wireless radios in accordance with the IEEE 802.22 (draft standard.

  14. Efficient Design of OFDMA-Based Programmable Wireless Radios

    Directory of Open Access Journals (Sweden)

    A. H. Tewfik

    2008-03-01

    Full Text Available With the increasing demand for efficient spectrum management, programmable wireless radios can potentially play a key role in shaping our future spectrum use. In this paper, we consider the design of low-power programmable wireless radios based on orthogonal frequency division multiple access (OFDMA. To meet the demands of higher data rate communications, we split OFDMA symbols carrying multiuser data across several noncontiguous bands of available spectrum. To relax power consumption in analog-to-digital and digital-to-analog converters, we use a programmable narrowband RF front end comprising of programmable synthesizers and fixed low-pass filters. To perform digital baseband signal processing in an energy efficient manner, we propose efficient designs for the fast Fourier transform (FFT and inverse FFT (IFFT modules. Our designs of the FFT/IFFT modules reduce power consumption and chip area, and are capable of handling the dynamic nature of spectrum in programmable radios. To recover data that falls within the transition band of the filters, we propose a combiner similar to maximal ratio combiner. We also present the complete design of programmable wireless radios in accordance with the IEEE 802.22 (draft standard.

  15. Flexible proportional-rate scheduling for OFDMA system

    KAUST Repository

    Leith, Alex; Alouini, Mohamed-Slim; Kim, Dongin; (Sherman) Shen X., Xuemin; Wu, Zhiqiang

    2013-01-01

    In this paper, we study the sum-rate maximization algorithms for downlink and uplink orthogonal frequency division multiple access (OFDMA) systems under proportional-rate constraint (PRC) and minimum-rate constraint. We develop a low-complexity weighted channel signal-to-noise ratio (w-SNR)-based ranking scheme for user selection on each subchannel in OFDMA combined with waterfilling (WF) power allocation. Both offline and online optimization algorithms are developed to optimize the SNR weight vector to maximize the sum rate while satisfying several constraints, such as PRC. The offline weight optimization technique relies on the analytical throughput results developed in this paper, and the online weight adaptation method tracks the user rates and meets the PRC using a subgradient search. Furthermore, we introduce a novel SNR operating region test to enhance the multiuser diversity gain and the sum rate. The proposed schemes have a low complexity, which is linear to the numbers of users and subchannels. Simulation results verify the accuracy of the developed analytical rates and fairness formulas, and show that the proposed w-SNR schemes can achieve higher sum rates than several benchmark schemes that provide the PRC with either short-term or long-term fairness. © 2013 IEEE. © 2013 ESO.

  16. Location-based resource allocation for OFDMA cognitive radio systems

    KAUST Repository

    Nam, Haewoon

    2010-01-01

    In cognitive radio systems, in order for the secondary users to opportunistically share the spectrum without interfering the primary users, an accurate spectrum measurement and a precise estimation of the interference at the primary users are necessary but are challenging tasks. Since it is impractical in cognitive radio systems to assume that the channel state information of the interference link is available at the cognitive transmitter, the interference at the primary users is hard to be estimated accurately. This paper introduces a resource allocation algorithm for OFDMA-based cognitive radio systems, which utilizes location information of the primary and secondary users instead of the channel state information of the interference link. Simulation results show that it is indeed effective to incorporate location information into resource allocation so that a near-optimal capacity is achieved.

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

    Science.gov (United States)

    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.

  18. Weighted-SNR-based fair scheduling for uplink OFDMA

    KAUST Repository

    Ma, Yao

    2009-11-01

    In this paper, we study the sum rate maximization algorithms with long-term proportional rate fairness (PRF) for uplink orthogonal frequency division multiple access (OFDMA) systems. In contrast to the rate-maximization schemes which used short-term PRF in the literature, we propose to use a selective multiuser diversity (SMuD) scheme to achieve a long-term PRF and improved sum rate performance. This scheme implements weighted channel signal-to-noise ratio (w-SNR)-based ranking for user selection on each subchannel, and then uses either water-filling (WF) or equal power allocation (EPA) along the assigned channels of each user. Both offline and online methods to find the optimal SNR weight factors are designed to achieve the target proportional rates for different users. The offline optimization technique requires to know the channel distribution information (CDI) at the scheduler. The online method uses the weight adaption combined with individual user rate tracking, which avoids the need to know the CDI. Analytical throughput metrics for the proposed w-SNR scheme with WF and EPA over Rayleigh channels are derived, and verified by simulations. Simulation results show that the proposed w-SNR PRF scheme can achieve significantly higher sum rates than the frequency diversity-based short-term and long-term fairness schemes. Besides the improved performance, the proposed schemes have a low complexity which is linear to numbers of users and subchannels.

  19. Sum rate maximization in the uplink of multi-cell OFDMA networks

    KAUST Repository

    Tabassum, Hina; Alouini, Mohamed-Slim; Dawy, Zaher

    2012-01-01

    of each cell, while ignoring the significant effect of inter-cell interference. This paper investigates the problem of resource allocation (i.e., subcarriers and powers) in the uplink of a multi-cell OFDMA network. The problem has a non

  20. Experimental demonstration of an improved EPON architecture using OFDMA for bandwidth scalable LAN emulation

    DEFF Research Database (Denmark)

    Deng, Lei; Zhao, Ying; Yu, Xianbin

    2011-01-01

    We propose and demonstrate an improved Ethernet passive optical network (EPON) architecture supporting bandwidth-scalable physical layer local area network (LAN) emulation. Due to the use of orthogonal frequency division multiple access (OFDMA) technology for the LAN traffic transmission, there i...

  1. Primal Decomposition-Based Method for Weighted Sum-Rate Maximization in Downlink OFDMA Systems

    Directory of Open Access Journals (Sweden)

    Weeraddana Chathuranga

    2010-01-01

    Full Text Available We consider the weighted sum-rate maximization problem in downlink Orthogonal Frequency Division Multiple Access (OFDMA systems. Motivated by the increasing popularity of OFDMA in future wireless technologies, a low complexity suboptimal resource allocation algorithm is obtained for joint optimization of multiuser subcarrier assignment and power allocation. The algorithm is based on an approximated primal decomposition-based method, which is inspired from exact primal decomposition techniques. The original nonconvex optimization problem is divided into two subproblems which can be solved independently. Numerical results are provided to compare the performance of the proposed algorithm to Lagrange relaxation based suboptimal methods as well as to optimal exhaustive search-based method. Despite its reduced computational complexity, the proposed algorithm provides close-to-optimal performance.

  2. Performance Analysis of Simple Channel Feedback Schemes for a Practical OFDMA System

    DEFF Research Database (Denmark)

    Pedersen, Klaus, I.; Kolding, Troels; Kovacs, Istvan

    2009-01-01

    In this paper, we evaluate the tradeoff between the amount of uplink channel feedback information and the orthogonal frequency-division multiple access (OFDMA) downlink performance with opportunistic frequency-domain packet scheduling. Three candidate channel feedback schemes are investigated......, including practical aspects, such as the effects of terminal measurement errors, bandwidth measurement granularity, quantization, and uplink signaling delays. The performance is evaluated by means of system-level simulations with detailed modeling of various radio resource-management algorithms, etc. Our...... results show that the optimal tradeoff between the channel feedback and the downlink OFDMA system performance depends on the radio channel frequency coherence bandwidth. We conclude that the so-called average best-M scheme is the most attractive channel feedback solution, where only the average channel...

  3. Distributed Synchronization Technique for OFDMA-Based Wireless Mesh Networks Using a Bio-Inspired Algorithm

    Directory of Open Access Journals (Sweden)

    Mi Jeong Kim

    2015-07-01

    Full Text Available In this paper, a distributed synchronization technique based on a bio-inspired algorithm is proposed for an orthogonal frequency division multiple access (OFDMA-based wireless mesh network (WMN with a time difference of arrival. The proposed time- and frequency-synchronization technique uses only the signals received from the neighbor nodes, by considering the effect of the propagation delay between the nodes. It achieves a fast synchronization with a relatively low computational complexity because it is operated in a distributed manner, not requiring any feedback channel for the compensation of the propagation delays. In addition, a self-organization scheme that can be effectively used to construct 1-hop neighbor nodes is proposed for an OFDMA-based WMN with a large number of nodes. The performance of the proposed technique is evaluated with regard to the convergence property and synchronization success probability using a computer simulation.

  4. Distributed Synchronization Technique for OFDMA-Based Wireless Mesh Networks Using a Bio-Inspired Algorithm.

    Science.gov (United States)

    Kim, Mi Jeong; Maeng, Sung Joon; Cho, Yong Soo

    2015-07-28

    In this paper, a distributed synchronization technique based on a bio-inspired algorithm is proposed for an orthogonal frequency division multiple access (OFDMA)-based wireless mesh network (WMN) with a time difference of arrival. The proposed time- and frequency-synchronization technique uses only the signals received from the neighbor nodes, by considering the effect of the propagation delay between the nodes. It achieves a fast synchronization with a relatively low computational complexity because it is operated in a distributed manner, not requiring any feedback channel for the compensation of the propagation delays. In addition, a self-organization scheme that can be effectively used to construct 1-hop neighbor nodes is proposed for an OFDMA-based WMN with a large number of nodes. The performance of the proposed technique is evaluated with regard to the convergence property and synchronization success probability using a computer simulation.

  5. Link adaptation algorithm for distributed coded transmissions in cooperative OFDMA systems

    DEFF Research Database (Denmark)

    Varga, Mihaly; Badiu, Mihai Alin; Bota, Vasile

    2015-01-01

    This paper proposes a link adaptation algorithm for cooperative transmissions in the down-link connection of an OFDMA-based wireless system. The algorithm aims at maximizing the spectral efficiency of a relay-aided communication link, while satisfying the block error rate constraints at both...... adaptation algorithm has linear complexity with the number of available resource blocks, while still provides a very good performance, as shown by simulation results....

  6. Application of WLF to OFDMA MU-MIMO Systems I: Frequency-Domain Equalization

    OpenAIRE

    Xiao, P; Lin, Z; Wu, Y; Schneider, C

    2013-01-01

    This paper presents a novel iterative receiver strategy incorporating widely linear filtering for uplink Orthogonal Frequency Division Multiple Access (OFDMA) multiuser multiple-input, multiple-output (MIMO) systems. The proposed iterative receiver scheme achieves better performance without the loss of spectrum efficiency compared to the conventional iterative receivers; The superiority of the investigated scheduler coupled with the innovative iterative receiver scheme over conventional solut...

  7. Analysis Framework for Opportunistic Spectrum OFDMA and its Application to the IEEE 802.22 Standard

    OpenAIRE

    Park, Jihoon; Pawełczak, Przemysław; Grønsund, Pål; Čabrić, Danijela

    2010-01-01

    We present an analytical model that enables throughput evaluation of Opportunistic Spectrum Orthogonal Frequency Division Multiple Access (OS-OFDMA) networks. The core feature of the model, based on a discrete time Markov chain, is the consideration of different channel and subchannel allocation strategies under different Primary and Secondary user types, traffic and priority levels. The analytical model also assesses the impact of different spectrum sensing strategies on the throughput of OS...

  8. Reduced feedback opportunistic and layered random beamforming for MIMO-OFDMA systems

    OpenAIRE

    Han, C; Nicolaou, M; Doufexi, A; Armour, SMD

    2007-01-01

    This paper considers a number of techniques employed in opportunistic and layered random beamforming OFDMA schemes that aim to reduce the feedback required to perform scheduling whilst also minimising the throughput degradations resulting from this reduced throughput (due to the lack of full CSI at the Base Station (BS). Frequency response correlation among subcarriers can be exploited to group adjacent subcarriers into clusters which can then be treated as a single unit for feedback purposes...

  9. Peak-to-average power ratio reduction in interleaved OFDMA systems

    KAUST Repository

    Al-Shuhail, Shamael; Ali, Anum; Al-Naffouri, Tareq Y.

    2015-01-01

    Orthogonal frequency division multiple access (OFDMA) systems suffer from several impairments, and communication system engineers use powerful signal processing tools to combat these impairments and to keep up with the capacity/rate demands. One of these impairments is high peak-to-average power ratio (PAPR) and clipping is the simplest peak reduction scheme. However, in general, when multiple users are subjected to clipping, frequency domain clipping distortions spread over the spectrum of all users. This results in compromised performance and hence clipping distortions need to be mitigated at the receiver. Mitigating these distortions in multiuser case is not simple and requires complex clipping mitigation procedures at the receiver. However, it was observed that interleaved OFDMA presents a special structure that results in only self-inflicted clipping distortions (i.e., the distortions of a particular user do not interfere with other users). In this work, we prove analytically that distortions do not spread over multiple users (while utilizing interleaved carrier assignment in OFDMA) and construct a compressed sensing system that utilizes the sparsity of the clipping distortions and recovers it on each user. We provide numerical results that validate our analysis and show promising performance for the proposed clipping recovery scheme.

  10. Peak-to-average power ratio reduction in interleaved OFDMA systems

    KAUST Repository

    Al-Shuhail, Shamael

    2015-12-07

    Orthogonal frequency division multiple access (OFDMA) systems suffer from several impairments, and communication system engineers use powerful signal processing tools to combat these impairments and to keep up with the capacity/rate demands. One of these impairments is high peak-to-average power ratio (PAPR) and clipping is the simplest peak reduction scheme. However, in general, when multiple users are subjected to clipping, frequency domain clipping distortions spread over the spectrum of all users. This results in compromised performance and hence clipping distortions need to be mitigated at the receiver. Mitigating these distortions in multiuser case is not simple and requires complex clipping mitigation procedures at the receiver. However, it was observed that interleaved OFDMA presents a special structure that results in only self-inflicted clipping distortions (i.e., the distortions of a particular user do not interfere with other users). In this work, we prove analytically that distortions do not spread over multiple users (while utilizing interleaved carrier assignment in OFDMA) and construct a compressed sensing system that utilizes the sparsity of the clipping distortions and recovers it on each user. We provide numerical results that validate our analysis and show promising performance for the proposed clipping recovery scheme.

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  12. Multiuser Carrier Frequency Offset Estimation for OFDMA Uplink Based on Multi-Antenna

    Science.gov (United States)

    Zhang, Weile; Wang, Junsong; Yin, Qinye; Feng, Ang

    In this letter, a novel method is proposed for carrier-frequency offset (CFO) estimation for multiple users in orthogonal frequency division multiple access (OFDMA) uplink with the generalized carrier assignment scheme (GCAS). The base station (BS) is equipped with multiple antennas, and each user's CFO can be estimated by the ESPRIT-like method that utilizes the rotation invariance of the space-domain snapshot matrix. The method is still effective even in fully loaded system with all subcarriers allocated to users. Simulation results illustrate the high performance of the proposed algorithm.

  13. Distributed Multi-Cell Resource Allocation with Price Based ICI Coordination in Downlink OFDMA Networks

    Science.gov (United States)

    Lv, Gangming; Zhu, Shihua; Hui, Hui

    Multi-cell resource allocation under minimum rate request for each user in OFDMA networks is addressed in this paper. Based on Lagrange dual decomposition theory, the joint multi-cell resource allocation problem is decomposed and modeled as a limited-cooperative game, and a distributed multi-cell resource allocation algorithm is thus proposed. Analysis and simulation results show that, compared with non-cooperative iterative water-filling algorithm, the proposed algorithm can remarkably reduce the ICI level and improve overall system performances.

  14. Spectrally Efficient OFDMA Lattice Structure via Toroidal Waveforms on the Time-Frequency Plane

    Directory of Open Access Journals (Sweden)

    Sultan Aldirmaz

    2010-01-01

    Full Text Available We investigate the performance of frequency division multiplexed (FDM signals, where multiple orthogonal Hermite-Gaussian carriers are used to increase the bandwidth efficiency. Multiple Hermite-Gaussian functions are modulated by a data set as a multicarrier modulation scheme in a single time-frequency region constituting toroidal waveform in a rectangular OFDMA system. The proposed work outperforms in the sense of bandwidth efficiency compared to the transmission scheme where only single Gaussian pulses are used as the transmission base. We investigate theoretical and simulation results of the proposed methods.

  15. Downlink Radio Resource Management for QoS Provisioning in OFDMA Systems

    DEFF Research Database (Denmark)

    Monghal, Guillaume Damien

    Admission Control solution for a realistic OFDMA based system in downlink where LTE is taken as a case study. In the frame of the thesis work, a detailed system model of LTE dedicated to Radio Resource Management study has been developed and implemented in a semi-static system level simulator. In a first...... phase, the study focuses on the dual time / frequency domain packet scheduling concept which allows a linear complexity. Fundamental design principles for throughput control are highlighted. Using those principles, the design of a complete Quality of Service aware packet scheduling algorithm based...

  16. A Priority-aware Frequency Domain Polling MAC Protocol for OFDMA-based Networks in Cyber-physical Systems

    Institute of Scientific and Technical Information of China (English)

    Meng Zheng; Junru Lin; Wei Liang; Haibin Yu

    2015-01-01

    Wireless networking in cyber-physical systems(CPSs) is characteristically different from traditional wireless systems due to the harsh radio frequency environment and applications that impose high real-time and reliability constraints.One of the fundamental considerations for enabling CPS networks is the medium access control protocol. To this end, this paper proposes a novel priority-aware frequency domain polling medium access control(MAC) protocol, which takes advantage of an orthogonal frequency-division multiple access(OFDMA)physical layer to achieve instantaneous priority-aware polling.Based on the polling result, the proposed work then optimizes the resource allocation of the OFDMA network to further improve the data reliability. Due to the non-polynomial-complete nature of the OFDMA resource allocation, we propose two heuristic rules,based on which an efficient solution algorithm to the OFDMA resource allocation problem is designed. Simulation results show that the reliability performance of CPS networks is significantly improved because of this work.

  17. Sum rate maximization in the uplink of multi-cell OFDMA networks

    KAUST Repository

    Tabassum, Hina

    2012-10-03

    Resource allocation in orthogonal frequency division multiple access (OFDMA) networks plays an imperative role to guarantee the system performance. However, most of the known resource allocation schemes are focused on maximizing the local throughput of each cell, while ignoring the significant effect of inter-cell interference. This paper investigates the problem of resource allocation (i.e., subcarriers and powers) in the uplink of a multi-cell OFDMA network. The problem has a non-convex combinatorial structure and is known to be NP hard. Firstly, we investigate the upper and lower bounds to the average network throughput due to the inherent complexity of implementing the optimal solution. Later, a centralized sub-optimal resource allocation scheme is developed. We further develop less complex centralized and distributed schemes that are well-suited for practical scenarios. The computational complexity of all schemes has been analyzed and the performance is compared through numerical simulations. Simulation results demonstrate that the distributed scheme achieves comparable performance to the centralized resource allocation scheme in various scenarios. © 2011 IEEE.

  18. Analytical Evaluation of Chunk-Based Tractable Multi-cell OFDMA system

    Directory of Open Access Journals (Sweden)

    P.Kavitha

    2018-04-01

    Full Text Available This paper evaluates thoroughly the performance of multi-cell OFDMA system. The two types of deployment in multi-cell OFDMA system, such as Strict Fractional Frequency Reuse (FFR and Soft FFR (SFR were evaluated. In order to model the base station locations, homogeneous Poisson point processes were used, i.e. tractable model instead of hexagonal grid was considered. In order to reduce complexity, chunk-based resource allocation scheme was embedded. Each cell divides the users into the users of the central cell area and the users of the cell edge area according to their average received Signal to Interference and Noise Ratio (SINR compared with FFR threshold. The primary stage of the analysis includes the spectral efficiency’s expression deriving from these two deployment scenarios, followed by the analysis with the use of coverage probability. However, the improvement of spectral efficiency is achieved in the case of SFR. On the contrary, coverage probability is far improved by using strict FFR scheme. Through numerical anaysis, We have shown that the optimal FFR threshold to achieve the highest spectral efficiency was 12 dB for both Strict FFR as well as SFR.

  19. Multiuser Scheduling on the Downlink of an LTE Cellular System

    Directory of Open Access Journals (Sweden)

    Raymond Kwan

    2008-01-01

    Full Text Available The challenge of scheduling user transmissions on the downlink of a long-term evolution (LTE cellular communication system is addressed. In particular, a novel optimalmultiuser scheduler is proposed. Numerical results show that the system performance improves with increasing correlation among OFDMA subcarriers. It is found that only a limited amount of feedback information is needed to achieve relatively good performance. A suboptimal reduced-complexity scheduler is also proposed and shown to provide good performance. The suboptimal scheme is especially attractive when the number of users is large, in which case the complexity of the optimal scheme is high.

  20. IQ imbalance tolerable parallel-channel DMT transmission for coherent optical OFDMA access network

    Science.gov (United States)

    Jung, Sang-Min; Mun, Kyoung-Hak; Jung, Sun-Young; Han, Sang-Kook

    2016-12-01

    Phase diversity of coherent optical communication provides spectrally efficient higher-order modulation for optical communications. However, in-phase/quadrature (IQ) imbalance in coherent optical communication degrades transmission performance by introducing unwanted signal distortions. In a coherent optical orthogonal frequency division multiple access (OFDMA) passive optical network (PON), IQ imbalance-induced signal distortions degrade transmission performance by interferences of mirror subcarriers, inter-symbol interference (ISI), and inter-channel interference (ICI). We propose parallel-channel discrete multitone (DMT) transmission to mitigate transceiver IQ imbalance-induced signal distortions in coherent orthogonal frequency division multiplexing (OFDM) transmissions. We experimentally demonstrate the effectiveness of parallel-channel DMT transmission compared with that of OFDM transmission in the presence of IQ imbalance.

  1. Error-rate performance analysis of cooperative OFDMA system with decode-and-forward relaying

    KAUST Repository

    Fareed, Muhammad Mehboob; Uysal, Murat; Tsiftsis, Theodoros A.

    2014-01-01

    In this paper, we investigate the performance of a cooperative orthogonal frequency-division multiple-access (OFDMA) system with decode-and-forward (DaF) relaying. Specifically, we derive a closed-form approximate symbol-error-rate expression and analyze the achievable diversity orders. Depending on the relay location, a diversity order up to (LSkD + 1) + σ M m = 1 min(LSkRm + 1, LR mD + 1) is available, where M is the number of relays, and LS kD + 1, LSkRm + 1, and LRmD + 1 are the lengths of channel impulse responses of source-to-destination, source-to- mth relay, and mth relay-to-destination links, respectively. Monte Carlo simulation results are also presented to confirm the analytical findings. © 2013 IEEE.

  2. Error-rate performance analysis of cooperative OFDMA system with decode-and-forward relaying

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-06-01

    In this paper, we investigate the performance of a cooperative orthogonal frequency-division multiple-access (OFDMA) system with decode-and-forward (DaF) relaying. Specifically, we derive a closed-form approximate symbol-error-rate expression and analyze the achievable diversity orders. Depending on the relay location, a diversity order up to (LSkD + 1) + σ M m = 1 min(LSkRm + 1, LR mD + 1) is available, where M is the number of relays, and LS kD + 1, LSkRm + 1, and LRmD + 1 are the lengths of channel impulse responses of source-to-destination, source-to- mth relay, and mth relay-to-destination links, respectively. Monte Carlo simulation results are also presented to confirm the analytical findings. © 2013 IEEE.

  3. Generalized location-based resource allocation for OFDMA cognitive radio systems

    KAUST Repository

    Ben Ghorbel, Mahdi

    2010-09-01

    Cognitive radio is one of the hot topics for emerging and future wireless communication. Cognitive users can share channels with primary users under the condition of non interference. In order to compute this interference, the cognitive system usually use the channel state information of the primary user which is often impractical to obtain. However, using location information, we can estimate this interference by pathloss computation. In this paper, we introduce a low-complexity resource allocation algorithm for orthogonal frequency division multiple access (OFDMA) based cognitive radio systems, which uses relative location information between primary and secondary users to estimate the interference. This algorithm considers interference with multiple primary users having different thresholds. The simulation results show the efficiency of the proposed algorithm by comparing it with an optimal exhaustive search method. © 2010 IEEE.

  4. Cognitive Aware Interference Mitigation Scheme for OFDMA Femtocells

    KAUST Repository

    Alqerm, Ismail

    2015-04-09

    Femto-cells deployment in today’s cellular networks came into practice to fulfill the increasing demand for data services. It also extends the coverage in the indoor areas. However, interference to other femto and macro-cells users remains an unresolved challenge. In this paper, we propose an interference mitigation scheme to control the cross-tier interference caused by femto-cells to the macro users and the co-tier interference among femtocells. Cognitive radio spectrum sensing capability is utilized to determine the non-occupied channels or the ones that cause minimal interference to the macro users. An awareness based channel allocation scheme is developed with the assistance of the graph-coloring algorithm to assign channels to the femto-cells base stations with power optimization, minimal interference, maximum throughput, and maximum spectrum efficiency. In addition, the scheme exploits negotiation capability to match traffic load and QoS with the channel, and to maintain efficient utilization of the available channels.

  5. Transmit Power Minimization and Base Station Planning for High-Speed Trains with Multiple Moving Relays in OFDMA Systems

    KAUST Repository

    Ghazzai, Hakim

    2016-03-15

    High-speed railway system equipped with moving relay stations placed on the middle of the ceiling of each train wagon is investigated. The users inside the train are served in two hops via the orthogonal frequency-division multiple access (OFDMA) technology. In this work, we first focus on minimizing the total downlink power consumption of the base station (BS) and the moving relays while respecting specific quality of service (QoS) constraints. We first derive the optimal resource allocation solution in terms of OFDMA subcarriers and power allocation using the dual decomposition method. Then, we propose an efficient algorithm based on the Hungarian method in order to find a suboptimal but low complexity solution. Moreover, we propose an OFDMA planning solution for high-speed train by finding the maximal inter-BS distance given the required user data rates in order to perform seamless handover. Our simulation results illustrate the performance of the proposed resource allocation schemes in the case of the 3GPP Long Term Evolution-Advanced (LTE-A) and compare them with previously developed algorithms as well as with the direct transmission scenario. Our results also highlight the significant planning gain obtained thanks to the use of multiple relays instead of the conventional single relay scenario.

  6. A cross-layer resource allocation scheme for spatial multiplexing-based MIMO-OFDMA systems

    Directory of Open Access Journals (Sweden)

    Al-Shatri Hussein

    2011-01-01

    Full Text Available Abstract We investigate the resource allocation problem for the downlink of a multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA system. The sum rate maximization itself cannot cope with fairness among users. Hence, we address this problem in the context of the utility-based resource allocation presented in earlier papers. This resource allocation method allows to enhance the efficiency and guarantee fairness among users by exploiting multiuser diversity, frequency diversity, as well as time diversity. In this paper, we treat the overall utility as the quality of service indicator and design utility functions with respect to the average transmission rate in order to simultaneously provide two services, real-time and best-effort. Since the optimal solutions are extremely computationally complex to obtain, we propose a suboptimal joint subchannel and power control algorithm that converges very fast and simplifies the MIMO resource allocation problem into a single-input single-output resource allocation problem. Simulation results indicate that using the proposed method achieves near-optimum solutions, and the available resources are distributed more fairly among users.

  7. Ant Colony Optimization Algorithm for Centralized Dynamic Channel Allocation in Multi-Cell OFDMA Systems

    Science.gov (United States)

    Kim, Hyo-Su; Kim, Dong-Hoi

    The dynamic channel allocation (DCA) scheme in multi-cell systems causes serious inter-cell interference (ICI) problem to some existing calls when channels for new calls are allocated. Such a problem can be addressed by advanced centralized DCA design that is able to minimize ICI. Thus, in this paper, a centralized DCA is developed for the downlink of multi-cell orthogonal frequency division multiple access (OFDMA) systems with full spectral reuse. However, in practice, as the search space of channel assignment for centralized DCA scheme in multi-cell systems grows exponentially with the increase of the number of required calls, channels, and cells, it becomes an NP-hard problem and is currently too complicated to find an optimum channel allocation. In this paper, we propose an ant colony optimization (ACO) based DCA scheme using a low-complexity ACO algorithm which is a kind of heuristic algorithm in order to solve the aforementioned problem. Simulation results demonstrate significant performance improvements compared to the existing schemes in terms of the grade of service (GoS) performance and the forced termination probability of existing calls without degrading the system performance of the average throughput.

  8. Fairness-Aware Energy-Efficient Resource Allocation for AF Co-Operative OFDMA Networks

    KAUST Repository

    Bedeer, Ebrahim; Alorainy, Abdulaziz; Hossain, Md. Jahangir; Amin, Osama; Alouini, Mohamed-Slim

    2015-01-01

    In this paper, we adopt an energy-efficiency (EE) metric, named worst-EE, that is suitable for EE fairness optimization in the uplink transmission of amplify-and-forward (AF) cooperative orthogonal frequency division multiple access (OFDMA) networks. More specifically, we assign subcarriers and allocate powers for mobile and relay stations in order to maximize the worst-EE, i.e., to maximize the EE of the mobile station (MS) with the lowest EE value, subject to MSs transmit power, relay station (RS) transmit power, and MSs quality-of-service (QoS) constraints. The formulated primal max-min optimization problem is nonconvex fractional mixed integer nonlinear program, i.e., NP-hard to solve. We provide a novel optimization framework that studies the structure of the primal problem and prove that the dual min-max optimization problem attains the same optimal solution of the primal problem. Additionally, we propose a modified Dinkelbach algorithm, named dual Dinkelbach, to achieve the optimal solution of the dual problem in a polynomial time complexity. We further exploit the structure of the obtained optimal solution and develop a low complexity suboptimal heuristic. Numerical results show the effectiveness of the proposed algorithm to improve the network performance in terms of fairness between MSs, worst-EE, and average network transmission rate when compared to traditional schemes that maximize the EE of the whole network. Presented results also show that the suboptimal heuristic balances the achieved performance and the computational complexity.

  9. Fairness-Aware Energy-Efficient Resource Allocation for AF Co-Operative OFDMA Networks

    KAUST Repository

    Bedeer, Ebrahim

    2015-09-23

    In this paper, we adopt an energy-efficiency (EE) metric, named worst-EE, that is suitable for EE fairness optimization in the uplink transmission of amplify-and-forward (AF) cooperative orthogonal frequency division multiple access (OFDMA) networks. More specifically, we assign subcarriers and allocate powers for mobile and relay stations in order to maximize the worst-EE, i.e., to maximize the EE of the mobile station (MS) with the lowest EE value, subject to MSs transmit power, relay station (RS) transmit power, and MSs quality-of-service (QoS) constraints. The formulated primal max-min optimization problem is nonconvex fractional mixed integer nonlinear program, i.e., NP-hard to solve. We provide a novel optimization framework that studies the structure of the primal problem and prove that the dual min-max optimization problem attains the same optimal solution of the primal problem. Additionally, we propose a modified Dinkelbach algorithm, named dual Dinkelbach, to achieve the optimal solution of the dual problem in a polynomial time complexity. We further exploit the structure of the obtained optimal solution and develop a low complexity suboptimal heuristic. Numerical results show the effectiveness of the proposed algorithm to improve the network performance in terms of fairness between MSs, worst-EE, and average network transmission rate when compared to traditional schemes that maximize the EE of the whole network. Presented results also show that the suboptimal heuristic balances the achieved performance and the computational complexity.

  10. Uplink Cross-Layer Scheduling with Differential QoS Requirements in OFDMA Systems

    Directory of Open Access Journals (Sweden)

    Chen Wei

    2010-01-01

    Full Text Available Fair and efficient scheduling is a key issue in cross-layer design for wireless communication systems, such as 3GPP LTE and WiMAX. However, few works have considered the multiaccess of the traffic with differential QoS requirements in wireless systems. In this paper, we will consider an OFDMA-based wireless system with four types of traffic associated with differential QoS requirements, namely, minimum reserved rate, maximum sustainable rate, maximum latency, and tolerant jitter. Given these QoS requirements, the traffic scheduling will be formulated into a cross-layer optimization problem, which is convex fortunately. By separating the power allocation through the waterfilling algorithm in each user, this problem will further reduce to a kind of continuous quadratic knapsack problem in the base station which yields low complexity. It is then demonstrated that the proposed cross-layer method cannot only guarantee the application layer QoS requirements, but also minimizes the integrated residual workload in the MAC layer. To further enhance the ability of QoS assurance in heavily loaded scenario, a call admission control scheme will also be proposed. The simulation results show that the QoS requirements for the four types of traffic are guaranteed effectively by the proposed algorithms.

  11. A coalition formation game for transmitter cooperation in OFDMA uplink communications

    KAUST Repository

    Chelli, Ali

    2014-12-01

    The SC-FDMA (single-carrier frequency division multiple access) is the access scheme that has been adopted by 3GPP (3rd generation partnership project) for the LTE (long term evolution) uplink. The SC-FDMA is an attractive alternative to OFDMA (orthogonal frequency-division multiple access) especially on the uplink owing to its low peak-to-average power ratio. This fact increases the power efficiency and reduces the cost of the power amplifiers at the mobile terminals. The use of SC-FDMA on the uplink implies that for highly loaded cells the base station allocates a single subcarrier to each user. This results in the limitation of the achievable rate on the uplink. In this work, we propose a coalition game between mobile terminals that allows them to improve their performance by sharing their subcarriers without creating any interference to each other. The proposed scheme allows a fair use of the subcarriers and leads to a significant capacity gain for each user. The cooperation between the nodes is modelled using coalitional game theory. In this game, each coalition tries to maximize its utility in terms of rate. In the absence of cooperation cost, it can be shown that the grand coalition is sum-rate optimal and stable, i.e., the mobile terminals have no incentive to leave the grand coalition.

  12. Cross-layer design for radio resource allocation based on priority scheduling in OFDMA wireless access network

    Directory of Open Access Journals (Sweden)

    Chen Yen-Wen

    2011-01-01

    Full Text Available Abstract The orthogonal frequency-division multiple access (OFDMA system has the advantages of flexible subcarrier allocation and adaptive modulation with respect to channel conditions. However, transmission overhead is required in each frame to broadcast the arrangement of radio resources to all mobile stations within the coverage of the same base station. This overhead greatly affects the utilization of valuable radio resources. In this paper, a cross layer scheme is proposed to reduce the number of traffic bursts at the downlink of an OFDMA wireless access network so that the overhead of the media access protocol (MAP field can be minimized. The proposed scheme considers the priorities and the channel conditions of quality of service (QoS traffic streams to arrange for them to be sent with minimum bursts in a heuristic manner. In addition, the trade-off between the degradation of the modulation level and the reduction of traffic bursts is investigated. Simulation results show that the proposed scheme can effectively reduce the traffic bursts and, therefore, increase resource utilization.

  13. Iterative Signal Processing for Mitigation of Analog-to-Digital Converter Clipping Distortion in Multiband OFDMA Receivers

    Directory of Open Access Journals (Sweden)

    Markus Allén

    2012-01-01

    Full Text Available In modern wideband communication receivers, the large input-signal dynamics is a fundamental problem. Unintentional signal clipping occurs, if the receiver front-end with the analog-to-digital interface cannot respond to rapidly varying conditions. This paper discusses digital postprocessing compensation of such unintentional clipping in multiband OFDMA receivers. The proposed method iteratively mitigates the clipping distortion by exploiting the symbol decisions. The performance of the proposed method is illustrated with various computer simulations and also verified by concrete laboratory measurements with commercially available analog-to-digital hardware. It is shown that the clipping compensation algorithm implemented in a turbo decoding OFDM receiver is able to remove almost all the clipping distortion even under significant clipping in fading channel circumstances. That is to say, it is possible to nearly recover the receiver performance to the level, which would be achieved in the equivalent nonclipped situation.

  14. Resource Allocation for OFDMA-Based Cognitive Radio Networks with Application to H.264 Scalable Video Transmission

    Directory of Open Access Journals (Sweden)

    Coon JustinP

    2011-01-01

    Full Text Available Resource allocation schemes for orthogonal frequency division multiple access- (OFDMA- based cognitive radio (CR networks that impose minimum and maximum rate constraints are considered. To demonstrate the practical application of such systems, we consider the transmission of scalable video sequences. An integer programming (IP formulation of the problem is presented, which provides the optimal solution when solved using common discrete programming methods. Due to the computational complexity involved in such an approach and its unsuitability for dynamic cognitive radio environments, we propose to use the method of lift-and-project to obtain a stronger formulation for the resource allocation problem such that the integrality gap between the integer program and its linear relaxation is reduced. A simple branching operation is then performed that eliminates any noninteger values at the output of the linear program solvers. Simulation results demonstrate that this simple technique results in solutions very close to the optimum.

  15. Cellular gravity

    NARCIS (Netherlands)

    F.C. Gruau; J.T. Tromp (John)

    1999-01-01

    textabstractWe consider the problem of establishing gravity in cellular automata. In particular, when cellular automata states can be partitioned into empty, particle, and wall types, with the latter enclosing rectangular areas, we desire rules that will make the particles fall down and pile up on

  16. Resource allocation for relay assisted cognitive radio networks

    KAUST Repository

    Zafar, Ammar; Alouini, Mohamed-Slim; Chen, Yunfei; Radaydeh, Redha M.

    2012-01-01

    transmission power and the relay transmission power. Numerical results show that the optimal sensing time is dependent on the primary user's signal-to-noise-ratio (SNR). They also show that SCR increases with increase in the number of relays. © 2012 IEEE.

  17. Resource allocation for relay assisted cognitive radio networks

    KAUST Repository

    Zafar, Ammar

    2012-09-16

    In this paper, we present two optimal resource allocation schemes that maximize throughput and symbol correct rate (SCR). The throughput and SCR are derived. The derived throughput and SCR are optimized with respect to the sensing time, the source transmission power and the relay transmission power. Numerical results show that the optimal sensing time is dependent on the primary user\\'s signal-to-noise-ratio (SNR). They also show that SCR increases with increase in the number of relays. © 2012 IEEE.

  18. Outage analysis for underlay relay-assisted cognitive networks

    KAUST Repository

    Tourki, Kamel; Qaraqe, Khalid A.; Alouini, Mohamed-Slim

    2012-01-01

    Cooperative relay technology was recently introduced into cognitive radio networks in order to enhance network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. We first provide the exact cumulative density function (CDF) of received signal-to-noise (SNR) over each hop with co-located relays. Then, the CDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. We validate our analysis by showing that simulation results coincide with our analytical results in Rayleigh fading channels. © 2012 IEEE.

  19. Outage analysis for underlay relay-assisted cognitive networks

    KAUST Repository

    Tourki, Kamel

    2012-12-01

    Cooperative relay technology was recently introduced into cognitive radio networks in order to enhance network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. We first provide the exact cumulative density function (CDF) of received signal-to-noise (SNR) over each hop with co-located relays. Then, the CDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. We validate our analysis by showing that simulation results coincide with our analytical results in Rayleigh fading channels. © 2012 IEEE.

  20. Cellular metabolism

    International Nuclear Information System (INIS)

    Hildebrand, C.E.; Walters, R.A.

    1977-01-01

    Progress is reported on the following research projects: chromatin structure; the use of circular synthetic polydeoxynucleotides as substrates for the study of DNA repair enzymes; human cellular kinetic response following exposure to DNA-interactive compounds; histone phosphorylation and chromatin structure in cell proliferation; photoaddition products induced in chromatin by uv light; pollutants and genetic information transfer; altered RNA metabolism as a function of cadmium accumulation and intracellular distribution in cultured cells; and thymidylate chromophore destruction by water free radicals

  1. Cellular dosimetry

    International Nuclear Information System (INIS)

    Humm, J.L.; Chin, L.M.

    1989-01-01

    Radiation dose is a useful predictive parameter for describing radiation toxicity in conventional radiotherapy. Traditionally, in vitro radiation biology dose-effect relations are expressed in the form of cell survival curves, a semilog plot of cell survival versus dose. However, the characteristic linear or linear quadratic survival curve shape, for high- and low-LET radiations respectively, is only strictly valid when the radiation dose is uniform across the entire target population. With an external beam of 60 Co gamma rays or x-rays, a uniform field may be readily achievable. When radionuclides are incorporated into a cell milieu, several new problems emerge which can result in a departure from uniformity in energy deposition throughout a cell population. This nonuniformity can have very important consequences for the shape of the survival curve. Cases in which perturbations of source uniformity may arise include: 1. Elemental sources may equilibrate in the cell medium with partition coefficients between the extracellular, cytosol, and nuclear compartments. The effect of preferential cell internalization or binding to cell membrane of some radionuclides can increase or decrease the slope of the survival curve. 2. Radionuclides bound to antibodies, hormones, metabolite precursors, etc., may result in a source localization pattern characteristic of the carrier agent, i.e., the sources may bind to cell surface receptors or antigens, be internalized, bind to secreted antigen concentrated around a fraction of the cell population, or become directly incorporated into the cell DNA. We propose to relate the distribution of energy deposition in cell nuclei to biological correlates of cellular inactivation. The probability of each cell's survival is weighted by its individual radiation burden, and the summation of these probabilities for the cell population can be used to predict the number or fraction of cell survivors

  2. Wireless Cellular Mobile Communications

    OpenAIRE

    Zalud, V.

    2002-01-01

    In this article is briefly reviewed the history of wireless cellular mobile communications, examined the progress in current second generation (2G) cellular standards and discussed their migration to the third generation (3G). The European 2G cellular standard GSM and its evolution phases GPRS and EDGE are described somewhat in detail. The third generation standard UMTS taking up on GSM/GPRS core network and equipped with a new advanced access network on the basis of code division multiple ac...

  3. Biomechanics of cellular solids.

    Science.gov (United States)

    Gibson, Lorna J

    2005-03-01

    Materials with a cellular structure are widespread in nature and include wood, cork, plant parenchyma and trabecular bone. Natural cellular materials are often mechanically efficient: the honeycomb-like microstructure of wood, for instance, gives it an exceptionally high performance index for resisting bending and buckling. Here we review the mechanics of a wide range of natural cellular materials and examine their role in lightweight natural sandwich structures (e.g. iris leaves) and natural tubular structures (e.g. plant stems or animal quills). We also describe two examples of engineered biomaterials with a cellular structure, designed to replace or regenerate tissue in the body.

  4. Linearizable cellular automata

    International Nuclear Information System (INIS)

    Nobe, Atsushi; Yura, Fumitaka

    2007-01-01

    The initial value problem for a class of reversible elementary cellular automata with periodic boundaries is reduced to an initial-boundary value problem for a class of linear systems on a finite commutative ring Z 2 . Moreover, a family of such linearizable cellular automata is given

  5. Heterogeneous cellular networks

    CERN Document Server

    Hu, Rose Qingyang

    2013-01-01

    A timely publication providing coverage of radio resource management, mobility management and standardization in heterogeneous cellular networks The topic of heterogeneous cellular networks has gained momentum in industry and the research community, attracting the attention of standardization bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are looking into increasing the capacity and coverage of the cellular networks. This book focuses on recent progresses,  covering the related topics including scenarios of heterogeneous network deployment, interference management i

  6. Cellular decomposition in vikalloys

    International Nuclear Information System (INIS)

    Belyatskaya, I.S.; Vintajkin, E.Z.; Georgieva, I.Ya.; Golikov, V.A.; Udovenko, V.A.

    1981-01-01

    Austenite decomposition in Fe-Co-V and Fe-Co-V-Ni alloys at 475-600 deg C is investigated. The cellular decomposition in ternary alloys results in the formation of bcc (ordered) and fcc structures, and in quaternary alloys - bcc (ordered) and 12R structures. The cellular 12R structure results from the emergence of stacking faults in the fcc lattice with irregular spacing in four layers. The cellular decomposition results in a high-dispersion structure and magnetic properties approaching the level of well-known vikalloys [ru

  7. Cellular Reflectarray Antenna

    Science.gov (United States)

    Romanofsky, Robert R.

    2010-01-01

    The cellular reflectarray antenna is intended to replace conventional parabolic reflectors that must be physically aligned with a particular satellite in geostationary orbit. These arrays are designed for specified geographical locations, defined by latitude and longitude, each called a "cell." A particular cell occupies nominally 1,500 square miles (3,885 sq. km), but this varies according to latitude and longitude. The cellular reflectarray antenna designed for a particular cell is simply positioned to align with magnetic North, and the antenna surface is level (parallel to the ground). A given cellular reflectarray antenna will not operate in any other cell.

  8. Magnetohydrodynamics cellular automata

    International Nuclear Information System (INIS)

    Hatori, Tadatsugu.

    1990-02-01

    There has been a renewal of interest in cellular automata, partly because they give an architecture for a special purpose computer with parallel processing optimized to solve a particular problem. The lattice gas cellular automata are briefly surveyed, which are recently developed to solve partial differential equations such as hydrodynamics or magnetohydrodynamics. A new model is given in the present paper to implement the magnetic Lorentz force in a more deterministic and local procedure than the previous one. (author)

  9. Epigenetics and Cellular Metabolism

    OpenAIRE

    Wenyi Xu; Fengzhong Wang; Zhongsheng Yu; Fengjiao Xin

    2016-01-01

    Living eukaryotic systems evolve delicate cellular mechanisms for responding to various environmental signals. Among them, epigenetic machinery (DNA methylation, histone modifications, microRNAs, etc.) is the hub in transducing external stimuli into transcriptional response. Emerging evidence reveals the concept that epigenetic signatures are essential for the proper maintenance of cellular metabolism. On the other hand, the metabolite, a main environmental input, can also influence the proce...

  10. Modeling cellular systems

    CERN Document Server

    Matthäus, Franziska; Pahle, Jürgen

    2017-01-01

    This contributed volume comprises research articles and reviews on topics connected to the mathematical modeling of cellular systems. These contributions cover signaling pathways, stochastic effects, cell motility and mechanics, pattern formation processes, as well as multi-scale approaches. All authors attended the workshop on "Modeling Cellular Systems" which took place in Heidelberg in October 2014. The target audience primarily comprises researchers and experts in the field, but the book may also be beneficial for graduate students.

  11. Magnetohydrodynamic cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Hatori, Tadatsugu [National Inst. for Fusion Science, Nagoya (Japan)

    1990-03-01

    There has been a renewal of interest in cellular automata, partly because they give an architecture for a special purpose computer with parallel processing optimized to solve a particular problem. The lattice gas cellular automata are briefly surveyed, which are recently developed to solve partial differential equations such as hydrodynamics or magnetohydrodynamics. A new model is given in the present paper to implement the magnetic Lorentz force in a more deterministic and local procedure than the previous one. (author).

  12. Magnetohydrodynamic cellular automata

    International Nuclear Information System (INIS)

    Hatori, Tadatsugu

    1990-01-01

    There has been a renewal of interest in cellular automata, partly because they give an architecture for a special purpose computer with parallel processing optimized to solve a particular problem. The lattice gas cellular automata are briefly surveyed, which are recently developed to solve partial differential equations such as hydrodynamics or magnetohydrodynamics. A new model is given in the present paper to implement the magnetic Lorentz force in a more deterministic and local procedure than the previous one. (author)

  13. Cellular MR Imaging

    Directory of Open Access Journals (Sweden)

    Michel Modo

    2005-07-01

    Full Text Available Cellular MR imaging is a young field that aims to visualize targeted cells in living organisms. In order to provide a different signal intensity of the targeted cell, they are either labeled with MR contrast agents in vivo or prelabeled in vitro. Either (ultrasmall superparamagnetic iron oxide [(USPIO] particles or (polymeric paramagnetic chelates can be used for this purpose. For in vivo cellular labeling, Gd3+- and Mn2+- chelates have mainly been used for targeted hepatobiliary imaging, and (USPIO-based cellular imaging has been focused on imaging of macrophage activity. Several of these magneto-pharmaceuticals have been FDA-approved or are in late-phase clinical trials. As for prelabeling of cells in vitro, a challenge has been to induce a sufficient uptake of contrast agents into nonphagocytic cells, without affecting normal cellular function. It appears that this issue has now largely been resolved, leading to an active research on monitoring the cellular biodistribution in vivo following transplantation or transfusion of these cells, including cell migration and trafficking. New applications of cellular MR imaging will be directed, for instance, towards our understanding of hematopoietic (immune cell trafficking and of novel guided (stem cell-based therapies aimed to be translated to the clinic in the future.

  14. Two-way DF relaying assisted D2D communication: ergodic rate and power allocation

    Science.gov (United States)

    Ni, Yiyang; Wang, Yuxi; Jin, Shi; Wong, Kai-Kit; Zhu, Hongbo

    2017-12-01

    In this paper, we investigate the ergodic rate for a device-to-device (D2D) communication system aided by a two-way decode-and-forward (DF) relay node. We first derive closed-form expressions for the ergodic rate of the D2D link under asymmetric and symmetric cases, respectively. We subsequently discuss two special scenarios including weak interference case and high signal-to-noise ratio case. Then we derive the tight approximations for each of the considered scenarios. Assuming that each transmitter only has access to its own statistical channel state information (CSI), we further derive closed-form power allocation strategy to improve the system performance according to the analytical results of the ergodic rate. Furthermore, some insights are provided for the power allocation strategy based on the analytical results. The strategies are easy to compute and require to know only the channel statistics. Numerical results show the accuracy of the analysis results under various conditions and test the availability of the power allocation strategy.

  15. Relay-assisted Network Coding Multicast in the Presence of Neighbours

    DEFF Research Database (Denmark)

    Khamfroush, Hana; Roetter, Daniel Enrique Lucani; Pahlevani, Peyman

    2015-01-01

    We study the problem of minimizing the cost of packet transmission from a source to two receivers with the help of a relay and using network coding in wireless mesh networks consisting of many active neighbours sharing the same channel. The cost minimization problem is modeled as a Markov Decisio...

  16. Relay-Assisted Primary and Secondary Transmissions in Cognitive Radio Networks

    KAUST Repository

    Shafie, Ahmed El; Khattab, Tamer; Salem, Ahmed Sultan

    2016-01-01

    We assume a set of cognitive relay nodes that assists both primary and secondary transmissions in a time-slotted cognitive radio networks. To regulate the channel access of the various nodes in the network, we propose an overlapped spectrum sensing

  17. Relay-Assisted Primary and Secondary Transmissions in Cognitive Radio Networks

    KAUST Repository

    Shafie, Ahmed El

    2016-09-27

    We assume a set of cognitive relay nodes that assists both primary and secondary transmissions in a time-slotted cognitive radio networks. To regulate the channel access of the various nodes in the network, we propose an overlapped spectrum sensing strategy for channel sensing, where the secondary source node senses the channel from the beginning of the time slot and the cognitive relay nodes sense the channel for double the sensing time used by the secondary source node to detect the activities of both the primary and secondary source nodes. Hence, the secondary source node has an intrinsic priority over the relay nodes. The relay nodes help both the primary user and the secondary user to deliver their unsuccessfully decoded packets at their destinations. In a given time slot, the scheduled relay node for data transmission starts its transmission when both the primary and secondary users are sensed to be inactive (i.e. have no data to transmit). We propose two optimization-based formulations with quality-of-service (QoS) constraints involving average queueing delay and average service rate requirements. We investigate both cases of perfect and imperfect spectrum sensing. To further enhance the users\\' QoS requirements, we propose three packet decoding strategies at the relay nodes and compare their performance. We derive an upper bound on the secondary queue average service rate to determine which decoding strategy can achieve that bound. Our numerical results show the benefits of relaying and its ability to enhance the performance of both the primary and secondary users. Moreover, the performance of the proposed schemes is close to the derived upper bound.

  18. Cellularized Cellular Solids via Freeze-Casting.

    Science.gov (United States)

    Christoph, Sarah; Kwiatoszynski, Julien; Coradin, Thibaud; Fernandes, Francisco M

    2016-02-01

    The elaboration of metabolically active cell-containing materials is a decisive step toward the successful application of cell based technologies. The present work unveils a new process allowing to simultaneously encapsulate living cells and shaping cell-containing materials into solid-state macroporous foams with precisely controlled morphology. Our strategy is based on freeze casting, an ice templating materials processing technique that has recently emerged for the structuration of colloids into macroporous materials. Our results indicate that it is possible to combine the precise structuration of the materials with cellular metabolic activity for the model organism Saccharomyces cerevisiae. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Epigenetics and Cellular Metabolism

    Directory of Open Access Journals (Sweden)

    Wenyi Xu

    2016-01-01

    Full Text Available Living eukaryotic systems evolve delicate cellular mechanisms for responding to various environmental signals. Among them, epigenetic machinery (DNA methylation, histone modifications, microRNAs, etc. is the hub in transducing external stimuli into transcriptional response. Emerging evidence reveals the concept that epigenetic signatures are essential for the proper maintenance of cellular metabolism. On the other hand, the metabolite, a main environmental input, can also influence the processing of epigenetic memory. Here, we summarize the recent research progress in the epigenetic regulation of cellular metabolism and discuss how the dysfunction of epigenetic machineries influences the development of metabolic disorders such as diabetes and obesity; then, we focus on discussing the notion that manipulating metabolites, the fuel of cell metabolism, can function as a strategy for interfering epigenetic machinery and its related disease progression as well.

  20. Wireless Cellular Mobile Communications

    Directory of Open Access Journals (Sweden)

    V. Zalud

    2002-12-01

    Full Text Available In this article is briefly reviewed the history of wireless cellularmobile communications, examined the progress in current secondgeneration (2G cellular standards and discussed their migration to thethird generation (3G. The European 2G cellular standard GSM and itsevolution phases GPRS and EDGE are described somewhat in detail. Thethird generation standard UMTS taking up on GSM/GPRS core network andequipped with a new advanced access network on the basis of codedivision multiple access (CDMA is investigated too. A sketch of theperspective of mobile communication beyond 3G concludes this article.

  1. Radiolabelled cellular blood elements

    International Nuclear Information System (INIS)

    Sinzinger, H.

    1990-01-01

    This book reports on radiolabelled cellular blood elements, covering new advances made during the past several years, in particular the use of Tc-99 as a tracer for blood elements. Coverage extends to several radiolabelled monoclonal antibodies that are specific for blood components and may label blood elements in vivo

  2. Building synthetic cellular organization

    OpenAIRE

    Polka, Jessica K.; Silver, Pamela A.

    2013-01-01

    The elaborate spatial organization of cells enhances, restricts, and regulates protein–protein interactions. However, the biological significance of this organization has been difficult to study without ways of directly perturbing it. We highlight synthetic biology tools for engineering novel cellular organization, describing how they have been, and can be, used to advance cell biology.

  3. The New Cellular Immunology

    Science.gov (United States)

    Claman, Henry N.

    1973-01-01

    Discusses the nature of the immune response and traces many of the discoveries that have led to the present state of knowledge in immunology. The new cellular immunology is directing its efforts toward improving health by proper manipulation of the immune mechanisms of the body. (JR)

  4. Electromagnetic cellular interactions.

    Science.gov (United States)

    Cifra, Michal; Fields, Jeremy Z; Farhadi, Ashkan

    2011-05-01

    Chemical and electrical interaction within and between cells is well established. Just the opposite is true about cellular interactions via other physical fields. The most probable candidate for an other form of cellular interaction is the electromagnetic field. We review theories and experiments on how cells can generate and detect electromagnetic fields generally, and if the cell-generated electromagnetic field can mediate cellular interactions. We do not limit here ourselves to specialized electro-excitable cells. Rather we describe physical processes that are of a more general nature and probably present in almost every type of living cell. The spectral range included is broad; from kHz to the visible part of the electromagnetic spectrum. We show that there is a rather large number of theories on how cells can generate and detect electromagnetic fields and discuss experimental evidence on electromagnetic cellular interactions in the modern scientific literature. Although small, it is continuously accumulating. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Genetic Dominance & Cellular Processes

    Science.gov (United States)

    Seager, Robert D.

    2014-01-01

    In learning genetics, many students misunderstand and misinterpret what "dominance" means. Understanding is easier if students realize that dominance is not a mechanism, but rather a consequence of underlying cellular processes. For example, metabolic pathways are often little affected by changes in enzyme concentration. This means that…

  6. Molecular and Cellular Signaling

    CERN Document Server

    Beckerman, Martin

    2005-01-01

    A small number of signaling pathways, no more than a dozen or so, form a control layer that is responsible for all signaling in and between cells of the human body. The signaling proteins belonging to the control layer determine what kinds of cells are made during development and how they function during adult life. Malfunctions in the proteins belonging to the control layer are responsible for a host of human diseases ranging from neurological disorders to cancers. Most drugs target components in the control layer, and difficulties in drug design are intimately related to the architecture of the control layer. Molecular and Cellular Signaling provides an introduction to molecular and cellular signaling in biological systems with an emphasis on the underlying physical principles. The text is aimed at upper-level undergraduates, graduate students and individuals in medicine and pharmacology interested in broadening their understanding of how cells regulate and coordinate their core activities and how diseases ...

  7. Nested cellular automata

    International Nuclear Information System (INIS)

    Quasthoff, U.

    1985-07-01

    Cellular automata by definition consist of a finite or infinite number of cells, say of unit length, with each cell having the same transition function. These cells are usually considered as the smallest elements and so the space filled with these cells becomes discrete. Nevertheless, large pictures created by such cellular automata look very fractal. So we try to replace each cell by a couple of smaller cells, which have the same transition functions as the large ones. There are automata where this replacement does not destroy the macroscopic structure. In these cases this nesting process can be iterated. The paper contains large classes of automata with the above properties. In the case of one dimensional automata with two states and next neighbour interaction and a nesting function of the same type a complete classification is given. (author)

  8. Predictability in cellular automata.

    Science.gov (United States)

    Agapie, Alexandru; Andreica, Anca; Chira, Camelia; Giuclea, Marius

    2014-01-01

    Modelled as finite homogeneous Markov chains, probabilistic cellular automata with local transition probabilities in (0, 1) always posses a stationary distribution. This result alone is not very helpful when it comes to predicting the final configuration; one needs also a formula connecting the probabilities in the stationary distribution to some intrinsic feature of the lattice configuration. Previous results on the asynchronous cellular automata have showed that such feature really exists. It is the number of zero-one borders within the automaton's binary configuration. An exponential formula in the number of zero-one borders has been proved for the 1-D, 2-D and 3-D asynchronous automata with neighborhood three, five and seven, respectively. We perform computer experiments on a synchronous cellular automaton to check whether the empirical distribution obeys also that theoretical formula. The numerical results indicate a perfect fit for neighbourhood three and five, which opens the way for a rigorous proof of the formula in this new, synchronous case.

  9. Probabilistic cellular automata.

    Science.gov (United States)

    Agapie, Alexandru; Andreica, Anca; Giuclea, Marius

    2014-09-01

    Cellular automata are binary lattices used for modeling complex dynamical systems. The automaton evolves iteratively from one configuration to another, using some local transition rule based on the number of ones in the neighborhood of each cell. With respect to the number of cells allowed to change per iteration, we speak of either synchronous or asynchronous automata. If randomness is involved to some degree in the transition rule, we speak of probabilistic automata, otherwise they are called deterministic. With either type of cellular automaton we are dealing with, the main theoretical challenge stays the same: starting from an arbitrary initial configuration, predict (with highest accuracy) the end configuration. If the automaton is deterministic, the outcome simplifies to one of two configurations, all zeros or all ones. If the automaton is probabilistic, the whole process is modeled by a finite homogeneous Markov chain, and the outcome is the corresponding stationary distribution. Based on our previous results for the asynchronous case-connecting the probability of a configuration in the stationary distribution to its number of zero-one borders-the article offers both numerical and theoretical insight into the long-term behavior of synchronous cellular automata.

  10. Wavefront cellular learning automata.

    Science.gov (United States)

    Moradabadi, Behnaz; Meybodi, Mohammad Reza

    2018-02-01

    This paper proposes a new cellular learning automaton, called a wavefront cellular learning automaton (WCLA). The proposed WCLA has a set of learning automata mapped to a connected structure and uses this structure to propagate the state changes of the learning automata over the structure using waves. In the WCLA, after one learning automaton chooses its action, if this chosen action is different from the previous action, it can send a wave to its neighbors and activate them. Each neighbor receiving the wave is activated and must choose a new action. This structure for the WCLA is necessary in many dynamic areas such as social networks, computer networks, grid computing, and web mining. In this paper, we introduce the WCLA framework as an optimization tool with diffusion capability, study its behavior over time using ordinary differential equation solutions, and present its accuracy using expediency analysis. To show the superiority of the proposed WCLA, we compare the proposed method with some other types of cellular learning automata using two benchmark problems.

  11. Algorithm for cellular reprogramming.

    Science.gov (United States)

    Ronquist, Scott; Patterson, Geoff; Muir, Lindsey A; Lindsly, Stephen; Chen, Haiming; Brown, Markus; Wicha, Max S; Bloch, Anthony; Brockett, Roger; Rajapakse, Indika

    2017-11-07

    The day we understand the time evolution of subcellular events at a level of detail comparable to physical systems governed by Newton's laws of motion seems far away. Even so, quantitative approaches to cellular dynamics add to our understanding of cell biology. With data-guided frameworks we can develop better predictions about, and methods for, control over specific biological processes and system-wide cell behavior. Here we describe an approach for optimizing the use of transcription factors (TFs) in cellular reprogramming, based on a device commonly used in optimal control. We construct an approximate model for the natural evolution of a cell-cycle-synchronized population of human fibroblasts, based on data obtained by sampling the expression of 22,083 genes at several time points during the cell cycle. To arrive at a model of moderate complexity, we cluster gene expression based on division of the genome into topologically associating domains (TADs) and then model the dynamics of TAD expression levels. Based on this dynamical model and additional data, such as known TF binding sites and activity, we develop a methodology for identifying the top TF candidates for a specific cellular reprogramming task. Our data-guided methodology identifies a number of TFs previously validated for reprogramming and/or natural differentiation and predicts some potentially useful combinations of TFs. Our findings highlight the immense potential of dynamical models, mathematics, and data-guided methodologies for improving strategies for control over biological processes. Copyright © 2017 the Author(s). Published by PNAS.

  12. Wavefront cellular learning automata

    Science.gov (United States)

    Moradabadi, Behnaz; Meybodi, Mohammad Reza

    2018-02-01

    This paper proposes a new cellular learning automaton, called a wavefront cellular learning automaton (WCLA). The proposed WCLA has a set of learning automata mapped to a connected structure and uses this structure to propagate the state changes of the learning automata over the structure using waves. In the WCLA, after one learning automaton chooses its action, if this chosen action is different from the previous action, it can send a wave to its neighbors and activate them. Each neighbor receiving the wave is activated and must choose a new action. This structure for the WCLA is necessary in many dynamic areas such as social networks, computer networks, grid computing, and web mining. In this paper, we introduce the WCLA framework as an optimization tool with diffusion capability, study its behavior over time using ordinary differential equation solutions, and present its accuracy using expediency analysis. To show the superiority of the proposed WCLA, we compare the proposed method with some other types of cellular learning automata using two benchmark problems.

  13. Environment Aware Cellular Networks

    KAUST Repository

    Ghazzai, Hakim

    2015-02-01

    The unprecedented rise of mobile user demand over the years have led to an enormous growth of the energy consumption of wireless networks as well as the greenhouse gas emissions which are estimated currently to be around 70 million tons per year. This significant growth of energy consumption impels network companies to pay huge bills which represent around half of their operating expenditures. Therefore, many service providers, including mobile operators, are looking for new and modern green solutions to help reduce their expenses as well as the level of their CO2 emissions. Base stations are the most power greedy element in cellular networks: they drain around 80% of the total network energy consumption even during low traffic periods. Thus, there is a growing need to develop more energy-efficient techniques to enhance the green performance of future 4G/5G cellular networks. Due to the problem of traffic load fluctuations in cellular networks during different periods of the day and between different areas (shopping or business districts and residential areas), the base station sleeping strategy has been one of the main popular research topics in green communications. In this presentation, we present several practical green techniques that provide significant gains for mobile operators. Indeed, combined with the base station sleeping strategy, these techniques achieve not only a minimization of the fossil fuel consumption but also an enhancement of mobile operator profits. We start with an optimized cell planning method that considers varying spatial and temporal user densities. We then use the optimal transport theory in order to define the cell boundaries such that the network total transmit power is reduced. Afterwards, we exploit the features of the modern electrical grid, the smart grid, as a new tool of power management for cellular networks and we optimize the energy procurement from multiple energy retailers characterized by different prices and pollutant

  14. Cosserat modeling of cellular solids

    NARCIS (Netherlands)

    Onck, P.R.

    Cellular solids inherit their macroscopic mechanical properties directly from the cellular microstructure. However, the characteristic material length scale is often not small compared to macroscopic dimensions, which limits the applicability of classical continuum-type constitutive models. Cosserat

  15. Evaluation of Structural Cellular Glass

    Science.gov (United States)

    Adams, M. A.; Zwissler, J. G.

    1984-01-01

    Preliminary design information presented. First report discusses state of structural-cellular-glass programs as of June 1979. Second report gives further details of program to develop improved cellular glasses and to characterize properties of glasses and commercially available materials.

  16. Cellular communication through light.

    Directory of Open Access Journals (Sweden)

    Daniel Fels

    Full Text Available Information transfer is a fundamental of life. A few studies have reported that cells use photons (from an endogenous source as information carriers. This study finds that cells can have an influence on other cells even when separated with a glass barrier, thereby disabling molecule diffusion through the cell-containing medium. As there is still very little known about the potential of photons for intercellular communication this study is designed to test for non-molecule-based triggering of two fundamental properties of life: cell division and energy uptake. The study was performed with a cellular organism, the ciliate Paramecium caudatum. Mutual exposure of cell populations occurred under conditions of darkness and separation with cuvettes (vials allowing photon but not molecule transfer. The cell populations were separated either with glass allowing photon transmission from 340 nm to longer waves, or quartz being transmittable from 150 nm, i.e. from UV-light to longer waves. Even through glass, the cells affected cell division and energy uptake in neighboring cell populations. Depending on the cuvette material and the number of cells involved, these effects were positive or negative. Also, while paired populations with lower growth rates grew uncorrelated, growth of the better growing populations was correlated. As there were significant differences when separating the populations with glass or quartz, it is suggested that the cell populations use two (or more frequencies for cellular information transfer, which influences at least energy uptake, cell division rate and growth correlation. Altogether the study strongly supports a cellular communication system, which is different from a molecule-receptor-based system and hints that photon-triggering is a fine tuning principle in cell chemistry.

  17. Engineering Cellular Metabolism

    DEFF Research Database (Denmark)

    Nielsen, Jens; Keasling, Jay

    2016-01-01

    Metabolic engineering is the science of rewiring the metabolism of cells to enhance production of native metabolites or to endow cells with the ability to produce new products. The potential applications of such efforts are wide ranging, including the generation of fuels, chemicals, foods, feeds...... of metabolic engineering and will discuss how new technologies can enable metabolic engineering to be scaled up to the industrial level, either by cutting off the lines of control for endogenous metabolism or by infiltrating the system with disruptive, heterologous pathways that overcome cellular regulation....

  18. Cellular mechanics and motility

    Science.gov (United States)

    Hénon, Sylvie; Sykes, Cécile

    2015-10-01

    The term motility defines the movement of a living organism. One widely known example is the motility of sperm cells, or the one of flagellar bacteria. The propulsive element of such organisms is a cilium(or flagellum) that beats. Although cells in our tissues do not have a flagellum in general, they are still able to move, as we will discover in this chapter. In fact, in both cases of movement, with or without a flagellum, cell motility is due to a dynamic re-arrangement of polymers inside the cell. Let us first have a closer look at the propulsion mechanism in the case of a flagellum or a cilium, which is the best known, but also the simplest, and which will help us to define the hydrodynamic general conditions of cell movement. A flagellum is sustained by cellular polymers arranged in semi-flexible bundles and flagellar beating generates cell displacement. These polymers or filaments are part of the cellular skeleton, or "cytoskeleton", which is, in this case, external to the cellular main body of the organism. In fact, bacteria move in a hydrodynamic regime in which viscosity dominates over inertia. The system is thus in a hydrodynamic regime of low Reynolds number (Box 5.1), which is nearly exclusively the case in all cell movements. Bacteria and their propulsion mode by flagella beating are our unicellular ancestors 3.5 billion years ago. Since then, we have evolved to form pluricellular organisms. However, to keep the ability of displacement, to heal our wounds for example, our cells lost their flagellum, since it was not optimal in a dense cell environment: cells are too close to each other to leave enough space for the flagella to accomplish propulsion. The cytoskeleton thus developed inside the cell body to ensure cell shape changes and movement, and also mechanical strength within a tissue. The cytoskeleton of our cells, like the polymers or filaments that sustain the flagellum, is also composed of semi-flexible filaments arranged in bundles, and also in

  19. Calibration and Evaluation of Fixed and Mobile Relay-Based System Level Simulator

    Directory of Open Access Journals (Sweden)

    Shahid Mumtaz

    2010-01-01

    Full Text Available Future wireless communication systems are expected to provide more stable and higher data rate transmissions in the whole OFDMA networks, but the mobile stations (MSs in the cell boundary experience poor spectral efficiency due to the path loss from the transmitting antenna and interference from adjacent cells. Therefore, satisfying QoS (Quality of Service requirements of each MS at the cell boundary has been an important issue. To resolve this spectral efficiency problem at the cell boundary, deploying relay stations has been actively considered. As multihop/relay has complex interactions between the routing and medium access control decisions, the extent to which analytical expressions can be used to explore its benefits is limited. Consequently, simulations tend to be the preferred way of assessing the performance of relays. In this paper, we evaluate the performance of relay-assisted OFDMA networks by means of system level simulator (SLS. We consistently observed that the throughput is increased and the outage is decreased in the relay-assisted OFDMA network, which is converted to range extension without any capacity penalty, for the realistic range of values of the propagation and other system parameters investigated.

  20. Cellular image classification

    CERN Document Server

    Xu, Xiang; Lin, Feng

    2017-01-01

    This book introduces new techniques for cellular image feature extraction, pattern recognition and classification. The authors use the antinuclear antibodies (ANAs) in patient serum as the subjects and the Indirect Immunofluorescence (IIF) technique as the imaging protocol to illustrate the applications of the described methods. Throughout the book, the authors provide evaluations for the proposed methods on two publicly available human epithelial (HEp-2) cell datasets: ICPR2012 dataset from the ICPR'12 HEp-2 cell classification contest and ICIP2013 training dataset from the ICIP'13 Competition on cells classification by fluorescent image analysis. First, the reading of imaging results is significantly influenced by one’s qualification and reading systems, causing high intra- and inter-laboratory variance. The authors present a low-order LP21 fiber mode for optical single cell manipulation and imaging staining patterns of HEp-2 cells. A focused four-lobed mode distribution is stable and effective in optical...

  1. Modeling and cellular studies

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    Testing the applicability of mathematical models with carefully designed experiments is a powerful tool in the investigations of the effects of ionizing radiation on cells. The modeling and cellular studies complement each other, for modeling provides guidance for designing critical experiments which must provide definitive results, while the experiments themselves provide new input to the model. Based on previous experimental results the model for the accumulation of damage in Chlamydomonas reinhardi has been extended to include various multiple two-event combinations. Split dose survival experiments have shown that models tested to date predict most but not all the observed behavior. Stationary-phase mammalian cells, required for tests of other aspects of the model, have been shown to be at different points in the cell cycle depending on how they were forced to stop proliferating. These cultures also demonstrate different capacities for repair of sublethal radiation damage

  2. Statistical mechanics of cellular automata

    International Nuclear Information System (INIS)

    Wolfram, S.

    1983-01-01

    Cellular automata are used as simple mathematical models to investigate self-organization in statistical mechanics. A detailed analysis is given of ''elementary'' cellular automata consisting of a sequence of sites with values 0 or 1 on a line, with each site evolving deterministically in discrete time steps according to p definite rules involving the values of its nearest neighbors. With simple initial configurations, the cellular automata either tend to homogeneous states, or generate self-similar patterns with fractal dimensions approx. =1.59 or approx. =1.69. With ''random'' initial configurations, the irreversible character of the cellular automaton evolution leads to several self-organization phenomena. Statistical properties of the structures generated are found to lie in two universality classes, independent of the details of the initial state or the cellular automaton rules. More complicated cellular automata are briefly considered, and connections with dynamical systems theory and the formal theory of computation are discussed

  3. 47 CFR 22.909 - Cellular markets.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cellular markets. 22.909 Section 22.909... Cellular Radiotelephone Service § 22.909 Cellular markets. Cellular markets are standard geographic areas used by the FCC for administrative convenience in the licensing of cellular systems. Cellular markets...

  4. MSAT and cellular hybrid networking

    Science.gov (United States)

    Baranowsky, Patrick W., II

    Westinghouse Electric Corporation is developing both the Communications Ground Segment and the Series 1000 Mobile Phone for American Mobile Satellite Corporation's (AMSC's) Mobile Satellite (MSAT) system. The success of the voice services portion of this system depends, to some extent, upon the interoperability of the cellular network and the satellite communication circuit switched communication channels. This paper will describe the set of user-selectable cellular interoperable modes (cellular first/satellite second, etc.) provided by the Mobile Phone and described how they are implemented with the ground segment. Topics including roaming registration and cellular-to-satellite 'seamless' call handoff will be discussed, along with the relevant Interim Standard IS-41 Revision B Cellular Radiotelecommunications Intersystem Operations and IOS-553 Mobile Station - Land Station Compatibility Specification.

  5. Cellular automata analysis and applications

    CERN Document Server

    Hadeler, Karl-Peter

    2017-01-01

    This book focuses on a coherent representation of the main approaches to analyze the dynamics of cellular automata. Cellular automata are an inevitable tool in mathematical modeling. In contrast to classical modeling approaches as partial differential equations, cellular automata are straightforward to simulate but hard to analyze. In this book we present a review of approaches and theories that allow the reader to understand the behavior of cellular automata beyond simulations. The first part consists of an introduction of cellular automata on Cayley graphs, and their characterization via the fundamental Cutis-Hedlund-Lyndon theorems in the context of different topological concepts (Cantor, Besicovitch and Weyl topology). The second part focuses on classification results: What classification follows from topological concepts (Hurley classification), Lyapunov stability (Gilman classification), and the theory of formal languages and grammars (Kůrka classification). These classifications suggest to cluster cel...

  6. MIMO Communication for Cellular Networks

    CERN Document Server

    Huang, Howard; Venkatesan, Sivarama

    2012-01-01

    As the theoretical foundations of multiple-antenna techniques evolve and as these multiple-input multiple-output (MIMO) techniques become essential for providing high data rates in wireless systems, there is a growing need to understand the performance limits of MIMO in practical networks. To address this need, MIMO Communication for Cellular Networks presents a systematic description of MIMO technology classes and a framework for MIMO system design that takes into account the essential physical-layer features of practical cellular networks. In contrast to works that focus on the theoretical performance of abstract MIMO channels, MIMO Communication for Cellular Networks emphasizes the practical performance of realistic MIMO systems. A unified set of system simulation results highlights relative performance gains of different MIMO techniques and provides insights into how best to use multiple antennas in cellular networks under various conditions. MIMO Communication for Cellular Networks describes single-user,...

  7. Programmable cellular arrays. Faults testing and correcting in cellular arrays

    International Nuclear Information System (INIS)

    Cercel, L.

    1978-03-01

    A review of some recent researches about programmable cellular arrays in computing and digital processing of information systems is presented, and includes both combinational and sequential arrays, with full arbitrary behaviour, or which can realize better implementations of specialized blocks as: arithmetic units, counters, comparators, control systems, memory blocks, etc. Also, the paper presents applications of cellular arrays in microprogramming, in implementing of a specialized computer for matrix operations, in modeling of universal computing systems. The last section deals with problems of fault testing and correcting in cellular arrays. (author)

  8. Top-down cellular pyramids

    Energy Technology Data Exchange (ETDEWEB)

    Wu, A Y; Rosenfeld, A

    1983-10-01

    A cellular pyramid is an exponentially tapering stack of arrays of processors (cells), where each cell is connected to its neighbors (siblings) on its own level, to a parent on the level above, and to its children on the level below. It is shown that in some situations, if information flows top-down only, from fathers to sons, then a cellular pyramid may be no faster than a one-level cellular array; but it may be possible to use simpler cells in the pyramid case. 23 references.

  9. Cellular senescence and organismal aging.

    Science.gov (United States)

    Jeyapalan, Jessie C; Sedivy, John M

    2008-01-01

    Cellular senescence, first observed and defined using in vitro cell culture studies, is an irreversible cell cycle arrest which can be triggered by a variety of factors. Emerging evidence suggests that cellular senescence acts as an in vivo tumor suppression mechanism by limiting aberrant proliferation. It has also been postulated that cellular senescence can occur independently of cancer and contribute to the physiological processes of normal organismal aging. Recent data have demonstrated the in vivo accumulation of senescent cells with advancing age. Some characteristics of senescent cells, such as the ability to modify their extracellular environment, could play a role in aging and age-related pathology. In this review, we examine current evidence that links cellular senescence and organismal aging.

  10. Origami interleaved tube cellular materials

    International Nuclear Information System (INIS)

    Cheung, Kenneth C; Tachi, Tomohiro; Calisch, Sam; Miura, Koryo

    2014-01-01

    A novel origami cellular material based on a deployable cellular origami structure is described. The structure is bi-directionally flat-foldable in two orthogonal (x and y) directions and is relatively stiff in the third orthogonal (z) direction. While such mechanical orthotropicity is well known in cellular materials with extruded two dimensional geometry, the interleaved tube geometry presented here consists of two orthogonal axes of interleaved tubes with high interfacial surface area and relative volume that changes with fold-state. In addition, the foldability still allows for fabrication by a flat lamination process, similar to methods used for conventional expanded two dimensional cellular materials. This article presents the geometric characteristics of the structure together with corresponding kinematic and mechanical modeling, explaining the orthotropic elastic behavior of the structure with classical dimensional scaling analysis. (paper)

  11. Origami interleaved tube cellular materials

    Science.gov (United States)

    Cheung, Kenneth C.; Tachi, Tomohiro; Calisch, Sam; Miura, Koryo

    2014-09-01

    A novel origami cellular material based on a deployable cellular origami structure is described. The structure is bi-directionally flat-foldable in two orthogonal (x and y) directions and is relatively stiff in the third orthogonal (z) direction. While such mechanical orthotropicity is well known in cellular materials with extruded two dimensional geometry, the interleaved tube geometry presented here consists of two orthogonal axes of interleaved tubes with high interfacial surface area and relative volume that changes with fold-state. In addition, the foldability still allows for fabrication by a flat lamination process, similar to methods used for conventional expanded two dimensional cellular materials. This article presents the geometric characteristics of the structure together with corresponding kinematic and mechanical modeling, explaining the orthotropic elastic behavior of the structure with classical dimensional scaling analysis.

  12. Cellular Angiofibroma of the Nasopharynx.

    Science.gov (United States)

    Erdur, Zülküf Burak; Yener, Haydar Murat; Yilmaz, Mehmet; Karaaltin, Ayşegül Batioğlu; Inan, Hakki Caner; Alaskarov, Elvin; Gozen, Emine Deniz

    2017-11-01

    Angiofibroma is a common tumor of the nasopharynx region but cellular type is extremely rare in head and neck. A 13-year-old boy presented with frequent epistaxis and nasal obstruction persisting for 6 months. According to the clinical symptoms and imaging studies juvenile angiofibroma was suspected. Following angiographic embolization total excision of the lesion by midfacial degloving approach was performed. Histological examination revealed that the tumor consisted of staghorn blood vessels and irregular fibrous stroma. Stellate fibroblasts with small pyknotic to large vesicular nuclei were seen in a highly cellular stroma. These findings identified cellular angiofibroma mimicking juvenile angiofibroma. This article is about a very rare patient of cellular angiofibroma of nasopharynx.

  13. Cellular-based preemption system

    Science.gov (United States)

    Bachelder, Aaron D. (Inventor)

    2011-01-01

    A cellular-based preemption system that uses existing cellular infrastructure to transmit preemption related data to allow safe passage of emergency vehicles through one or more intersections. A cellular unit in an emergency vehicle is used to generate position reports that are transmitted to the one or more intersections during an emergency response. Based on this position data, the one or more intersections calculate an estimated time of arrival (ETA) of the emergency vehicle, and transmit preemption commands to traffic signals at the intersections based on the calculated ETA. Additional techniques may be used for refining the position reports, ETA calculations, and the like. Such techniques include, without limitation, statistical preemption, map-matching, dead-reckoning, augmented navigation, and/or preemption optimization techniques, all of which are described in further detail in the above-referenced patent applications.

  14. Novel Materials for Cellular Nanosensors

    DEFF Research Database (Denmark)

    Sasso, Luigi

    The monitoring of cellular behavior is useful for the advancement of biomedical diagnostics, drug development and the understanding of a cell as the main unit of the human body. Micro- and nanotechnology allow for the creation of functional devices that enhance the study of cellular dynamics...... modifications for electrochemical nanosensors for the detection of analytes released from cells. Two type of materials were investigated, each pertaining to the two different aspects of such devices: peptide nanostructures were studied for the creation of cellular sensing substrates that mimic in vivo surfaces...... and that offer advantages of functionalization, and conducting polymers were used as electrochemical sensor surface modifications for increasing the sensitivity towards relevant analytes, with focus on the detection of dopamine released from cells via exocytosis. Vertical peptide nanowires were synthesized from...

  15. Global properties of cellular automata

    International Nuclear Information System (INIS)

    Jen, E.

    1986-01-01

    Cellular automata are discrete mathematical systems that generate diverse, often complicated, behavior using simple deterministic rules. Analysis of the local structure of these rules makes possible a description of the global properties of the associated automata. A class of cellular automata that generate infinitely many aperoidic temporal sequences is defined,a s is the set of rules for which inverses exist. Necessary and sufficient conditions are derived characterizing the classes of ''nearest-neighbor'' rules for which arbitrary finite initial conditions (i) evolve to a homogeneous state; (ii) generate at least one constant temporal sequence

  16. Cellular structures with interconnected microchannels

    Science.gov (United States)

    Shaefer, Robert Shahram; Ghoniem, Nasr M.; Williams, Brian

    2018-01-30

    A method for fabricating a cellular tritium breeder component includes obtaining a reticulated carbon foam skeleton comprising a network of interconnected ligaments. The foam skeleton is then melt-infiltrated with a tritium breeder material, for example, lithium zirconate or lithium titanate. The foam skeleton is then removed to define a cellular breeder component having a network of interconnected tritium purge channels. In an embodiment the ligaments of the foam skeleton are enlarged by adding carbon using chemical vapor infiltration (CVI) prior to melt-infiltration. In an embodiment the foam skeleton is coated with a refractory material, for example, tungsten, prior to melt infiltration.

  17. Cellular uptake of metallated cobalamins

    DEFF Research Database (Denmark)

    Tran, Mai Thanh Quynh; Stürup, Stefan; Lambert, Ian Henry

    2016-01-01

    Cellular uptake of vitamin B12-cisplatin conjugates was estimated via detection of their metal constituents (Co, Pt, and Re) by inductively coupled plasma mass spectrometry (ICP-MS). Vitamin B12 (cyano-cob(iii)alamin) and aquo-cob(iii)alamin [Cbl-OH2](+), which differ in the β-axial ligands (CN...

  18. Repaglinide at a cellular level

    DEFF Research Database (Denmark)

    Krogsgaard Thomsen, M; Bokvist, K; Høy, M

    2002-01-01

    To investigate the hormonal and cellular selectivity of the prandial glucose regulators, we have undertaken a series of experiments, in which we characterised the effects of repaglinide and nateglinide on ATP-sensitive potassium ion (KATP) channel activity, membrane potential and exocytosis in ra...

  19. Cellular automaton for surface reactions

    Energy Technology Data Exchange (ETDEWEB)

    Pechatnikov, E L [AN SSSR, Chernogolovka (Russian Federation). Otdelenie Inst. Khimicheskoj Fiziki; Frankowicz, A; Danielak, R [Uniwersytet Jagiellonski, Cracow (Poland)

    1994-06-01

    A new algorithm which overcomes some specific difficulties arising in modeling of heterogeneous catalytic processes by cellular automata (CA) technique is proposed. The algorithm was tested with scheme introduced by Ziff, Gulari and Barshad and showed a good agreement with their results. The problem of the physical adequacy and interpretation of the algorithm was discussed. (author). 10 refs, 4 figs.

  20. Cellular Automata and the Humanities.

    Science.gov (United States)

    Gallo, Ernest

    1994-01-01

    The use of cellular automata to analyze several pre-Socratic hypotheses about the evolution of the physical world is discussed. These hypotheses combine characteristics of both rigorous and metaphoric language. Since the computer demands explicit instructions for each step in the evolution of the automaton, such models can reveal conceptual…

  1. Cellular buckling in long structures

    NARCIS (Netherlands)

    Hunt, G.W.; Peletier, M.A.; Champneys, A.R.; Woods, P.D.; Wadee, M.A.; Budd, C.J.; Lord, G.J.

    2000-01-01

    A long structural system with an unstable (subcritical)post-buckling response that subsequently restabilizes typically deformsin a cellular manner, with localized buckles first forming and thenlocking up in sequence. As buckling continues over a growing number ofcells, the response can be described

  2. Joint Bandwidth and Power Allocation for MIMO Two-Way Relays-Assisted Overlay Cognitive Radio Systems

    KAUST Repository

    Alsharoa, Ahmad; Ghazzai, Hakim; Yaacoub, Elias; Alouini, Mohamed-Slim; Kamal, Ahmed

    2015-01-01

    This paper studies the achievable cognitive sum rate of an overlay cognitive radio (CR) system assisted with multiple antennas two-way relays in which primary users (PUs) cooperate with cognitive users (CUs) for mutual benefits. In this context, the problem of both bandwidth and power allocation is investigated. We propose that the CUs are allowed to allocate a part of the PUs spectrum to perform their cognitive transmission. In return, acting as amplify-and-forward two-way relays, they are exploited to support PUs to reach their target data rates over the remaining bandwidth. Power expressions for optimal transmit power allocated per PU and CU antenna are derived under primary quality-of-service constraint in addition to bandwidth and power budget constraints. More specifically, CUs act as relays for the PUs transmission and gain some spectrum as long as they respect these constraints. After deriving the optimal transmit powers, we employ a strong optimization tool based on swarm intelligence to optimize the full and complex relay amplification gain matrices in addition to the bandwidths released to primary and cognitive transmission. Furthermore, three different utility functions are considered in our optimization problems depending on the level of fairness among CUs.

  3. Performance analysis of relay-assisted all-optical FSO networks over strong atmospheric turbulence channels with pointing errors

    KAUST Repository

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

    2014-01-01

    -optical links. Assuming a variable gain relay with amplify-and-forward protocol, the electrical signal at the source is forwarded to the destination with the help of this relay through all-optical links. More specifically, we first present a cumulative density

  4. Joint Bandwidth and Power Allocation for MIMO Two-Way Relays-Assisted Overlay Cognitive Radio Systems

    KAUST Repository

    Alsharoa, Ahmad

    2015-10-08

    This paper studies the achievable cognitive sum rate of an overlay cognitive radio (CR) system assisted with multiple antennas two-way relays in which primary users (PUs) cooperate with cognitive users (CUs) for mutual benefits. In this context, the problem of both bandwidth and power allocation is investigated. We propose that the CUs are allowed to allocate a part of the PUs spectrum to perform their cognitive transmission. In return, acting as amplify-and-forward two-way relays, they are exploited to support PUs to reach their target data rates over the remaining bandwidth. Power expressions for optimal transmit power allocated per PU and CU antenna are derived under primary quality-of-service constraint in addition to bandwidth and power budget constraints. More specifically, CUs act as relays for the PUs transmission and gain some spectrum as long as they respect these constraints. After deriving the optimal transmit powers, we employ a strong optimization tool based on swarm intelligence to optimize the full and complex relay amplification gain matrices in addition to the bandwidths released to primary and cognitive transmission. Furthermore, three different utility functions are considered in our optimization problems depending on the level of fairness among CUs.

  5. Universal map for cellular automata

    International Nuclear Information System (INIS)

    García-Morales, V.

    2012-01-01

    A universal map is derived for all deterministic 1D cellular automata (CAs) containing no freely adjustable parameters and valid for any alphabet size and any neighborhood range (including non-symmetrical neighborhoods). The map can be extended to an arbitrary number of dimensions and topologies and to arbitrary order in time. Specific CA maps for the famous Conway's Game of Life and Wolfram's 256 elementary CAs are given. An induction method for CAs, based in the universal map, allows mathematical expressions for the orbits of a wide variety of elementary CAs to be systematically derived. -- Highlights: ► A universal map is derived for all deterministic 1D cellular automata (CA). ► The map is generalized to 2D for Von Neumann, Moore and hexagonal neighborhoods. ► A map for all Wolfram's 256 elementary CAs is derived. ► A map for Conway's “Game of Life” is obtained.

  6. Simulating physics with cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Vichniac, G Y

    1984-01-01

    Cellular automata are dynamical systems where space, time, and variables are discrete. They are shown on two-dimensional examples to be capable of non-numerical simulations of physics. They are useful for faithful parallel processing of lattice models. At another level, they exhibit behaviours and illustrate concepts that are unmistakably physical, such as non-ergodicity and order parameters, frustration, relaxation to chaos through period doublings, a conspicuous arrow of time in reversible microscopic dynamics, causality and light-cone, and non-separability. In general, they constitute exactly computable models for complex phenomena and large-scale correlations that result from very simple short-range interactions. The author studies their space, time, and intrinsic symmetries and the corresponding conservation laws, with an emphasis on the conservation of information obeyed by reversible cellular automata. 60 references.

  7. Cellular Adhesion and Adhesion Molecules

    OpenAIRE

    SELLER, Zerrin

    2014-01-01

    In recent years, cell adhesion and cell adhesion molecules have been shown to be important for many normal biological processes, including embryonic cell migration, immune system functions and wound healing. It has also been shown that they contribute to the pathogenesis of a large number of common human disorders, such as rheumatoid arthritis and tumor cell metastasis in cancer. In this review, the basic mechanisms of cellular adhesion and the structural and functional features of adhes...

  8. Cellular automata with voting rule

    International Nuclear Information System (INIS)

    Makowiec, D.

    1996-01-01

    The chosen local interaction - the voting (majority) rule applied to the square lattice is known to cause the non ergodic cellular automata behaviour. Presented computer simulation results verify two cases of non ergodicity. The first one is implicated by the noise introduced to the local interactions and the second one follows properties of the initial lattice configuration selected at random. For the simplified voting rule - non symmetric voting, the critical behaviour has been explained rigorously. (author)

  9. Cellular communications a comprehensive and practical guide

    CERN Document Server

    Tripathi, Nishith

    2014-01-01

    Even as newer cellular technologies and standards emerge, many of the fundamental principles and the components of the cellular network remain the same. Presenting a simple yet comprehensive view of cellular communications technologies, Cellular Communications provides an end-to-end perspective of cellular operations, ranging from physical layer details to call set-up and from the radio network to the core network. This self-contained source forpractitioners and students represents a comprehensive survey of the fundamentals of cellular communications and the landscape of commercially deployed

  10. The cellular approach to band structure calculations

    International Nuclear Information System (INIS)

    Verwoerd, W.S.

    1982-01-01

    A short introduction to the cellular approach in band structure calculations is given. The linear cellular approach and its potantial applicability in surface structure calculations is given some consideration in particular

  11. [Cellular subcutaneous tissue. Anatomic observations].

    Science.gov (United States)

    Marquart-Elbaz, C; Varnaison, E; Sick, H; Grosshans, E; Cribier, B

    2001-11-01

    We showed in a companion paper that the definition of the French "subcutaneous cellular tissue" considerably varied from the 18th to the end of the 20th centuries and has not yet reached a consensus. To address the anatomic reality of this "subcutaneous cellular tissue", we investigated the anatomic structures underlying the fat tissue in normal human skin. Sixty specimens were excised from the surface to the deep structures (bone, muscle, cartilage) on different body sites of 3 cadavers from the Institut d'Anatomie Normale de Strasbourg. Samples were paraffin-embedded, stained and analysed with a binocular microscope taking x 1 photographs. Specimens were also excised and fixed after subcutaneous injection of Indian ink, after mechanic tissue splitting and after performing artificial skin folds. The aspects of the deep parts of the skin greatly varied according to their anatomic localisation. Below the adipose tissue, we often found a lamellar fibrous layer which extended from the interlobular septa and contained horizontally distributed fat cells. No specific tissue below the hypodermis was observed. Artificial skin folds concerned either exclusively the dermis, when they were superficial or included the hypodermis, but no specific structure was apparent in the center of the fold. India ink diffused to the adipose tissue, mainly along the septa, but did not localise in a specific subcutaneous compartment. This study shows that the histologic aspects of the deep part of the skin depend mainly on the anatomic localisation. Skin is composed of epidermis, dermis and hypodermis and thus the hypodermis can not be considered as being "subcutaneous". A difficult to individualise, fibrous lamellar structure in continuity with the interlobular septa is often found under the fat lobules. This structure is a cleavage line, as is always the case with loose connective tissues, but belongs to the hypodermis (i.e. fat tissue). No specific tissue nor any virtual space was

  12. Zeno's paradox in quantum cellular automata

    International Nuclear Information System (INIS)

    Groessing, G.; Zeilinger, A.

    1991-01-01

    The effect of Zeno's paradox in quantum theory is demonstrated with the aid of quantum mechanical cellular automata. It is shown that the degree of non-unitarity of the cellular automaton evolution and the frequency of consecutive measurements of cellular automaton states are operationally indistinguishable. (orig.)

  13. Zeno's paradox in quantum cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Groessing, G [Atominst. der Oesterreichischen Universitaeten, Vienna (Austria); Zeilinger, A [Inst. fuer Experimentalphysik, Univ. Innsbruck (Austria)

    1991-07-01

    The effect of Zeno's paradox in quantum theory is demonstrated with the aid of quantum mechanical cellular automata. It is shown that the degree of non-unitarity of the cellular automaton evolution and the frequency of consecutive measurements of cellular automaton states are operationally indistinguishable. (orig.).

  14. Game of Life Cellular Automata

    CERN Document Server

    Adamatzky, Andrew

    2010-01-01

    In the late 1960s, British mathematician John Conway invented a virtual mathematical machine that operates on a two-dimensional array of square cell. Each cell takes two states, live and dead. The cells' states are updated simultaneously and in discrete time. A dead cell comes to life if it has exactly three live neighbours. A live cell remains alive if two or three of its neighbours are alive, otherwise the cell dies. Conway's Game of Life became the most programmed solitary game and the most known cellular automaton. The book brings together results of forty years of study into computational

  15. 'Biomoleculas': cellular metabolism didactic software

    International Nuclear Information System (INIS)

    Menghi, M L; Novella, L P; Siebenlist, M R

    2007-01-01

    'Biomoleculas' is a software that deals with topics such as the digestion, cellular metabolism and excretion of nutrients. It is a pleasant, simple and didactic guide, made by and for students. In this program, each biomolecule (carbohydrates, lipids and proteins) is accompanied until its degradation and assimilation by crossing and interrelating the different metabolic channels to finally show the destination of the different metabolites formed and the way in which these are excreted. It is used at present as a teaching-learning process tool by the chair of Physiology and Biophysics at the Facultad de Ingenieria - Universidad Nacional de Entre Rios

  16. Symmetry analysis of cellular automata

    International Nuclear Information System (INIS)

    García-Morales, V.

    2013-01-01

    By means of B-calculus [V. García-Morales, Phys. Lett. A 376 (2012) 2645] a universal map for deterministic cellular automata (CAs) has been derived. The latter is shown here to be invariant upon certain transformations (global complementation, reflection and shift). When constructing CA rules in terms of rules of lower range a new symmetry, “invariance under construction” is uncovered. Modular arithmetic is also reformulated within B-calculus and a new symmetry of certain totalistic CA rules, which calculate the Pascal simplices modulo an integer number p, is then also uncovered.

  17. On two integrable cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Bobenko, A [Technische Univ. Berlin (Germany). Fachbereich Mathematik; Bordemann, M [Freiburg Univ. (Germany). Fachbereich Physik; Gunn, C [Technische Univ. Berlin (Germany). Fachbereich Mathematik; Pinkall, U [Technische Univ. Berlin (Germany). Fachbereich Mathematik

    1993-11-01

    We describe two simple cellular automata (CA) models which exhibit the essential attributes of soliton systems. The first one is an invertible, 2-state, 1-dimensional CA or, in other words, a nonlinear Z[sub 2]-valued dynamical system with discrete space and time. Against a vacuum state of 0, the system exhibits light cone particles in both spatial directions, which interact in a soliton-like fashion. A complete solution of this system is obtained. We also consider another CA, which is described by the Hirota equation over a finite field, and present a Lax representation for it. (orig.)

  18. Cellular automata a parallel model

    CERN Document Server

    Mazoyer, J

    1999-01-01

    Cellular automata can be viewed both as computational models and modelling systems of real processes. This volume emphasises the first aspect. In articles written by leading researchers, sophisticated massive parallel algorithms (firing squad, life, Fischer's primes recognition) are treated. Their computational power and the specific complexity classes they determine are surveyed, while some recent results in relation to chaos from a new dynamic systems point of view are also presented. Audience: This book will be of interest to specialists of theoretical computer science and the parallelism challenge.

  19. Melanoma screening with cellular phones.

    Directory of Open Access Journals (Sweden)

    Cesare Massone

    Full Text Available BACKGROUND: Mobile teledermatology has recently been shown to be suitable for teledermatology despite limitations in image definition in preliminary studies. The unique aspect of mobile teledermatology is that this system represents a filtering or triage system, allowing a sensitive approach for the management of patients with emergent skin diseases. METHODOLOGY/PRINCIPAL FINDINGS: In this study we investigated the feasibility of teleconsultation using a new generation of cellular phones in pigmented skin lesions. 18 patients were selected consecutively in the Pigmented Skin Lesions Clinic of the Department of Dermatology, Medical University of Graz, Graz (Austria. Clinical and dermoscopic images were acquired using a Sony Ericsson with a built-in two-megapixel camera. Two teleconsultants reviewed the images on a specific web application (http://www.dermahandy.net/default.asp where images had been uploaded in JPEG format. Compared to the face-to-face diagnoses, the two teleconsultants obtained a score of correct telediagnoses of 89% and of 91.5% reporting the clinical and dermoscopic images, respectively. CONCLUSIONS/SIGNIFICANCE: The present work is the first study performing mobile teledermoscopy using cellular phones. Mobile teledermatology has the potential to become an easy applicable tool for everyone and a new approach for enhanced self-monitoring for skin cancer screening in the spirit of the eHealth program of the European Commission Information for Society and Media.

  20. 47 CFR 22.970 - Unacceptable interference to part 90 non-cellular 800 MHz licensees from cellular radiotelephone...

    Science.gov (United States)

    2010-10-01

    ...-cellular 800 MHz licensees from cellular radiotelephone or part 90-800 MHz cellular systems. 22.970 Section... MOBILE SERVICES Cellular Radiotelephone Service § 22.970 Unacceptable interference to part 90 non-cellular 800 MHz licensees from cellular radiotelephone or part 90-800 MHz cellular systems. (a) Definition...

  1. Molecular, cellular, and tissue engineering

    CERN Document Server

    Bronzino, Joseph D

    2015-01-01

    Known as the bible of biomedical engineering, The Biomedical Engineering Handbook, Fourth Edition, sets the standard against which all other references of this nature are measured. As such, it has served as a major resource for both skilled professionals and novices to biomedical engineering. Molecular, Cellular, and Tissue Engineering, the fourth volume of the handbook, presents material from respected scientists with diverse backgrounds in molecular biology, transport phenomena, physiological modeling, tissue engineering, stem cells, drug delivery systems, artificial organs, and personalized medicine. More than three dozen specific topics are examined, including DNA vaccines, biomimetic systems, cardiovascular dynamics, biomaterial scaffolds, cell mechanobiology, synthetic biomaterials, pluripotent stem cells, hematopoietic stem cells, mesenchymal stem cells, nanobiomaterials for tissue engineering, biomedical imaging of engineered tissues, gene therapy, noninvasive targeted protein and peptide drug deliver...

  2. Pressure-actuated cellular structures

    International Nuclear Information System (INIS)

    Pagitz, M; Hol, J M A M; Lamacchia, E

    2012-01-01

    Shape changing structures will play an important role in future engineering designs since rigid structures are usually only optimal for a small range of service conditions. Hence, a concept for reliable and energy-efficient morphing structures that possess a large strength to self-weight ratio would be widely applicable. We propose a novel concept for morphing structures that is inspired by the nastic movement of plants. The idea is to connect prismatic cells with tailored pentagonal and/or hexagonal cross sections such that the resulting cellular structure morphs into given target shapes for certain cell pressures. An efficient algorithm for computing equilibrium shapes as well as cross-sectional geometries is presented. The potential of this novel concept is demonstrated by several examples that range from a flagellum like propulsion device to a morphing aircraft wing.

  3. Cellular automata in cytoskeletal lattices

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S A; Watt, R C; Hameroff, S R

    1984-01-01

    Cellular automata (CA) activities could mediate biological regulation and information processing via nonlinear electrodynamic effects in cytoskeletal lattice arrays. Frohlich coherent oscillations and other nonlinear mechanisms may effect discrete 10/sup -10/ to 10/sup -11/ s interval events which result in dynamic patterns in biolattices such as cylindrical protein polymers: microtubules (MT). Structural geometry and electrostatic forces of MT subunit dipole oscillations suggest neighbor rules among the hexagonally packed protein subunits. Computer simulations using these suggested rules and MT structural geometry demonstrate CA activities including dynamical and stable self-organizing patterns, oscillators, and traveling gliders. CA activities in MT and other cytoskeletal lattices may have important biological regulatory functions. 23 references, 6 figures, 1 table.

  4. Sensing Phosphatidylserine in Cellular Membranes

    Directory of Open Access Journals (Sweden)

    Jason G. Kay

    2011-01-01

    Full Text Available Phosphatidylserine, a phospholipid with a negatively charged head-group, is an important constituent of eukaryotic cellular membranes. On the plasma membrane, rather than being evenly distributed, phosphatidylserine is found preferentially in the inner leaflet. Disruption of this asymmetry, leading to the appearance of phosphatidylserine on the surface of the cell, is known to play a central role in both apoptosis and blood clotting. Despite its importance, comparatively little is known about phosphatidylserine in cells: its precise subcellular localization, transmembrane topology and intracellular dynamics are poorly characterized. The recent development of new, genetically-encoded probes able to detect phosphatidylserine within live cells, however, is leading to a more in-depth understanding of the biology of this phospholipid. This review aims to give an overview of the current methods for phosphatidylserine detection within cells, and some of the recent realizations derived from their use.

  5. A radiation measurement study on cellular phone

    International Nuclear Information System (INIS)

    Mohd Yusof Mohd Ali; Rozaimah Abd Rahim; Roha Tukimin; Khairol Nizam Mohamed; Mohd Amirul Nizam Mohamad Thari; Ahmad Fadzli Ahmad Sanusi

    2007-01-01

    This paper will explain the radiation level produced by various selected cellular phone from various models and brands available in the market. The result obtained from this study will also recommend whether a cellular phone is safe for public usage or it might cause any effect on public health. Finally, a database of radiation measurement level produced by selected various cellular phone will also be developed and exhibited in this paper. (Author)

  6. Outer-totalistic cellular automata on graphs

    International Nuclear Information System (INIS)

    Marr, Carsten; Huett, Marc-Thorsten

    2009-01-01

    We present an intuitive formalism for implementing cellular automata on arbitrary topologies. By that means, we identify a symmetry operation in the class of elementary cellular automata. Moreover, we determine the subset of topologically sensitive elementary cellular automata and find that the overall number of complex patterns decreases under increasing neighborhood size in regular graphs. As exemplary applications, we apply the formalism to complex networks and compare the potential of scale-free graphs and metabolic networks to generate complex dynamics

  7. Radiation, nitric oxide and cellular death

    International Nuclear Information System (INIS)

    Dubner, D.; Perez, M.R. Del; Michelin, S.C.; Gisone, P.A.

    1997-01-01

    The mechanisms of radiation induced cellular death constitute an objective of research ever since the first biological effects of radiation were first observed. The explosion of information produced in the last 20 years calls for a careful analysis due to the apparent contradictory data related to the cellular system studied and the range of doses used. This review focuses on the role of the active oxygen species, in particular the nitric oxides, in its relevance as potential mediator of radiation induced cellular death

  8. Cellular Targets of Dietary Polyphenol Resveratrol

    National Research Council Canada - National Science Library

    Wu, Joseph M

    2006-01-01

    To test the hypothesis that resveratrol, a grape derived polyphenol, exerts its chemopreventive properties against prostate cancer by interacting with specific cellular targets, denoted resveratrol targeting proteins (RTPs...

  9. The cellular memory disc of reprogrammed cells.

    Science.gov (United States)

    Anjamrooz, Seyed Hadi

    2013-04-01

    The crucial facts underlying the low efficiency of cellular reprogramming are poorly understood. Cellular reprogramming occurs in nuclear transfer, induced pluripotent stem cell (iPSC) formation, cell fusion, and lineage-switching experiments. Despite these advances, there are three fundamental problems to be addressed: (1) the majority of cells cannot be reprogrammed, (2) the efficiency of reprogramming cells is usually low, and (3) the reprogrammed cells developed from a patient's own cells activate immune responses. These shortcomings present major obstacles for using reprogramming approaches in customised cell therapy. In this Perspective, the author synthesises past and present observations in the field of cellular reprogramming to propose a theoretical picture of the cellular memory disc. The current hypothesis is that all cells undergo an endogenous and exogenous holographic memorisation such that parts of the cellular memory dramatically decrease the efficiency of reprogramming cells, act like a barrier against reprogramming in the majority of cells, and activate immune responses. Accordingly, the focus of this review is mainly to describe the cellular memory disc (CMD). Based on the present theory, cellular memory includes three parts: a reprogramming-resistance memory (RRM), a switch-promoting memory (SPM) and a culture-induced memory (CIM). The cellular memory arises genetically, epigenetically and non-genetically and affects cellular behaviours. [corrected].

  10. Infiltrating giant cellular blue naevus.

    Science.gov (United States)

    Bittencourt, A L; Monteiro, D A; De Pretto, O J

    2007-01-01

    Cellular blue naevi (CBN) measure 1-2 cm in diameter and affect the dermis, occasionally extending into the subcutaneous fat. The case of a 14-year-old boy with a giant CBN (GCBN) involving the right half of the face, the jugal mucosa and the lower eyelid with a tumour that had infiltrated the bone and the maxillary and ethmoidal sinuses is reported. Biopsies were taken from the skin, jugal mucosa and maxillary sinus. The following markers were used in the immunohistochemical evaluation: CD34, CD56, HMB-45, anti-S100, A-103, Melan A and MIB-1. The biopsy specimens showed a biphasic pattern affecting the lower dermis, subcutaneous fat, skeletal muscle, bone, jugal mucosa and maxillary sinus, but there was no histological evidence of malignancy. The tumour cells were CD34-, CD56-, HMB45+, anti-S100+ and A-103+. Melan A was focally expressed. No positive MIB-1 cells were identified. The present case shows that GCBN may infiltrate deeply, with no evidence of malignancy.

  11. Diselenolane-mediated cellular uptake.

    Science.gov (United States)

    Chuard, Nicolas; Poblador-Bahamonde, Amalia I; Zong, Lili; Bartolami, Eline; Hildebrandt, Jana; Weigand, Wolfgang; Sakai, Naomi; Matile, Stefan

    2018-02-21

    The emerging power of thiol-mediated uptake with strained disulfides called for a move from sulfur to selenium. We report that according to results with fluorescent model substrates, cellular uptake with 1,2-diselenolanes exceeds uptake with 1,2-dithiolanes and epidithiodiketopiperazines with regard to efficiency as well as intracellular localization. The diselenide analog of lipoic acid performs best. This 1,2-diselenolane delivers fluorophores efficiently to the cytosol of HeLa Kyoto cells, without detectable endosomal capture as with 1,2-dithiolanes or dominant escape into the nucleus as with epidithiodiketopiperazines. Diselenolane-mediated cytosolic delivery is non-toxic (MTT assay), sensitive to temperature but insensitive to inhibitors of endocytosis (chlorpromazine, methyl-β-cyclodextrin, wortmannin, cytochalasin B) and conventional thiol-mediated uptake (Ellman's reagent), and to serum. Selenophilicity, the extreme CSeSeC dihedral angle of 0° and the high but different acidity of primary and secondary selenols might all contribute to uptake. Thiol-exchange affinity chromatography is introduced as operational mimic of thiol-mediated uptake that provides, in combination with rate enhancement of DTT oxidation, direct experimental evidence for existence and nature of the involved selenosulfides.

  12. Cellular Senescence: A Translational Perspective

    Directory of Open Access Journals (Sweden)

    James L. Kirkland

    2017-07-01

    Full Text Available Cellular senescence entails essentially irreversible replicative arrest, apoptosis resistance, and frequently acquisition of a pro-inflammatory, tissue-destructive senescence-associated secretory phenotype (SASP. Senescent cells accumulate in various tissues with aging and at sites of pathogenesis in many chronic diseases and conditions. The SASP can contribute to senescence-related inflammation, metabolic dysregulation, stem cell dysfunction, aging phenotypes, chronic diseases, geriatric syndromes, and loss of resilience. Delaying senescent cell accumulation or reducing senescent cell burden is associated with delay, prevention, or alleviation of multiple senescence-associated conditions. We used a hypothesis-driven approach to discover pro-survival Senescent Cell Anti-apoptotic Pathways (SCAPs and, based on these SCAPs, the first senolytic agents, drugs that cause senescent cells to become susceptible to their own pro-apoptotic microenvironment. Several senolytic agents, which appear to alleviate multiple senescence-related phenotypes in pre-clinical models, are beginning the process of being translated into clinical interventions that could be transformative.

  13. Re: Epigenetics of Cellular Reprogramming

    Directory of Open Access Journals (Sweden)

    Fehmi Narter

    2016-12-01

    Full Text Available EDITORIAL COMMENT Cells have some specific molecular and physiological properties that act their functional process. However, many cells have an ability of efficient transition from one type to another. This ability is named plasticity. This process occurs due to epigenetic reprogramming that involves changes in transcription and chromatin structure. Some changes during reprogramming that have been identified in recent years as genomic demethylation (both histone and DNA, histone acetylation and loss of heterochromatin during the development of many diseases such as infertility and cancer progression. In this review, the authors focused on the latest work addressing the mechanisms surrounding the epigenetic regulation of various types of reprogramming, including somatic cell nuclear transfer, cell fusion and transcription factor- and microRNA-induced pluripotency. There are many responsible factors such as genes, cytokines, proteins, co-factors (i.e. vitamin C in this local area network. The exact mechanisms by which these changes are achieved and the detailed interplay between the players responsible, however, remain relatively unclear. In the treatment of diseases, such as infertility, urooncology, reconstructive urology, etc., epigenetic changes and cellular reprogramming will be crucial in the near future. Central to achieving that goal is a more thorough understanding of the epigenetic state of fully reprogrammed cells. By the progress of researches on this topic, new treatment modalities will be identified for these diseases.

  14. Efficiency of cellular information processing

    International Nuclear Information System (INIS)

    Barato, Andre C; Hartich, David; Seifert, Udo

    2014-01-01

    We show that a rate of conditional Shannon entropy reduction, characterizing the learning of an internal process about an external process, is bounded by the thermodynamic entropy production. This approach allows for the definition of an informational efficiency that can be used to study cellular information processing. We analyze three models of increasing complexity inspired by the Escherichia coli sensory network, where the external process is an external ligand concentration jumping between two values. We start with a simple model for which ATP must be consumed so that a protein inside the cell can learn about the external concentration. With a second model for a single receptor we show that the rate at which the receptor learns about the external environment can be nonzero even without any dissipation inside the cell since chemical work done by the external process compensates for this learning rate. The third model is more complete, also containing adaptation. For this model we show inter alia that a bacterium in an environment that changes at a very slow time-scale is quite inefficient, dissipating much more than it learns. Using the concept of a coarse-grained learning rate, we show for the model with adaptation that while the activity learns about the external signal the option of changing the methylation level increases the concentration range for which the learning rate is substantial. (paper)

  15. Pulsed feedback defers cellular differentiation.

    Directory of Open Access Journals (Sweden)

    Joe H Levine

    2012-01-01

    Full Text Available Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable "polyphasic" positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a "timer" that operates over timescales much longer than a cell cycle.

  16. Cellular phone use while driving at night.

    Science.gov (United States)

    Vivoda, Jonathon M; Eby, David W; St Louis, Renée M; Kostyniuk, Lidia P

    2008-03-01

    Use of a cellular phone has been shown to negatively affect one's attention to the driving task, leading to an increase in crash risk. At any given daylight hour, about 6% of US drivers are actively talking on a hand-held cell phone. However, previous surveys have focused only on cell phone use during the day. Driving at night has been shown to be a riskier activity than driving during the day. The purpose of the current study was to assess the rate of hand-held cellular phone use while driving at night, using specialized night vision equipment. In 2006, two statewide direct observation survey waves of nighttime cellular phone use were conducted in Indiana utilizing specialized night vision equipment. Combined results of driver hand-held cellular phone use from both waves are presented in this manuscript. The rates of nighttime cell phone use were similar to results found in previous daytime studies. The overall rate of nighttime hand-held cellular phone use was 5.8 +/- 0.6%. Cellular phone use was highest for females and for younger drivers. In fact, the highest rate observed during the study (of 11.9%) was for 16-to 29-year-old females. The high level of cellular phone use found within the young age group, coupled with the increased crash risk associated with cellular phone use, nighttime driving, and for young drivers in general, suggests that this issue may become an important transportation-related concern.

  17. On Elementary and Algebraic Cellular Automata

    Science.gov (United States)

    Gulak, Yuriy

    In this paper we study elementary cellular automata from an algebraic viewpoint. The goal is to relate the emergent complex behavior observed in such systems with the properties of corresponding algebraic structures. We introduce algebraic cellular automata as a natural generalization of elementary ones and discuss their applications as generic models of complex systems.

  18. Cellular Factors Shape 3D Genome Landscape

    Science.gov (United States)

    Researchers, using novel large-scale imaging technology, have mapped the spatial location of individual genes in the nucleus of human cells and identified 50 cellular factors required for the proper 3D positioning of genes. These spatial locations play important roles in gene expression, DNA repair, genome stability, and other cellular activities.

  19. Cellular chain formation in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Klemm, Per

    2009-01-01

    ; type I fimbriae expression significantly reduced cellular chain formation, presumably by steric hindrance. Cellular chain formation did not appear to be specific to E coli K-12. Although many urinary tract infection (UTI) isolates were found to form rather homogeneous, flat biofilms, three isolates...

  20. Estimating cellular network performance during hurricanes

    International Nuclear Information System (INIS)

    Booker, Graham; Torres, Jacob; Guikema, Seth; Sprintson, Alex; Brumbelow, Kelly

    2010-01-01

    Cellular networks serve a critical role during and immediately after a hurricane, allowing citizens to contact emergency services when land-line communication is lost and serving as a backup communication channel for emergency responders. However, due to their ubiquitous deployment and limited design for extreme loading events, basic network elements, such as cellular towers and antennas are prone to failures during adverse weather conditions such as hurricanes. Accordingly, a systematic and computationally feasible approach is required for assessing and improving the reliability of cellular networks during hurricanes. In this paper we develop a new multi-disciplinary approach to efficiently and accurately assess cellular network reliability during hurricanes. We show how the performance of a cellular network during and immediately after future hurricanes can be estimated based on a combination of hurricane wind field models, structural reliability analysis, Monte Carlo simulation, and cellular network models and simulation tools. We then demonstrate the use of this approach for assessing the improvement in system reliability that can be achieved with discrete topological changes in the system. Our results suggest that adding redundancy, particularly through a mesh topology or through the addition of an optical fiber ring around the perimeter of the system can be an effective way to significantly increase the reliability of some cellular systems during hurricanes.

  1. Imaging in cellular and tissue engineering

    CERN Document Server

    Yu, Hanry

    2013-01-01

    Details on specific imaging modalities for different cellular and tissue engineering applications are scattered throughout articles and chapters in the literature. Gathering this information into a single reference, Imaging in Cellular and Tissue Engineering presents both the fundamentals and state of the art in imaging methods, approaches, and applications in regenerative medicine. The book underscores the broadening scope of imaging applications in cellular and tissue engineering. It covers a wide range of optical and biological applications, including the repair or replacement of whole tiss

  2. Advanced 3D Printers for Cellular Solids

    Science.gov (United States)

    2016-06-30

    06-2016 1-Aug-2014 31-Dec-2015 Final Report: Advanced 3D printers for Cellular Solids The views, opinions and/or findings contained in this report are...2211 3d printing, cellular solids REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8...Papers published in non peer-reviewed journals: Final Report: Advanced 3D printers for Cellular Solids Report Title Final Report for DURIP grant W911NF

  3. Cellularity of certain quantum endomorphism algebras

    DEFF Research Database (Denmark)

    Andersen, Henning Haahr; Lehrer, G. I.; Zhang, R.

    Let $\\tA=\\Z[q^{\\pm \\frac{1}{2}}][([d]!)\\inv]$ and let $\\Delta_{\\tA}(d)$ be an integral form of the Weyl module of highest weight $d \\in \\N$ of the quantised enveloping algebra $\\U_{\\tA}$ of $\\fsl_2$. We exhibit for all positive integers $r$ an explicit cellular structure for $\\End...... of endomorphism algebras, and another which relates the multiplicities of indecomposable summands to the dimensions of simple modules for an endomorphism algebra. Our cellularity result then allows us to prove that knowledge of the dimensions of the simple modules of the specialised cellular algebra above...

  4. CELLULAR INTERACTIONS MEDIATED BY GLYCONECTIDS

    Directory of Open Access Journals (Sweden)

    O.Popescu

    1999-01-01

    Full Text Available Cellular interactions involve many types of cell surface molecules and operate via homophilic and/or heterophilic protein-protein and protein-carbohydrate binding. Our investigations in different model-systems (marine invertebrates and mammals have provided direct evidence that a novel class of primordial proteoglycans, named by us gliconectins, can mediate cell adhesion via a new alternative molecular mechanism of polyvalent carbohydrate-carbohydrate binding. Biochemical characterization of isolated and purified glyconectins revealed the presence of specific carbohydrate structures, acidic glycans, different from classical glycosaminoglycans. Such acidic glycans of high molecular weight containing fucose, glucuronic or galacturonic acids, and sulfate groups, originally found in sponges and sea urchin embryos, may represent a new class of carbohydrate carcino-embryonal antigens in mice and humans. Such interactions between biological macromolecules are usually investigated by kinetic binding studies, calorimetric methods, X-ray diffraction, nuclear magnetic resonance, and other spectroscopic analyses. However, these methods do not supply a direct estimation of the intermolecular binding forces that are fundamental for the function of the ligand-receptor association. Recently, we have introduced atomic force microscopy to quantify the binding strength between cell adhesion proteoglycans. Measurement of binding forces intrinsic to cell adhesion proteoglycans is necessary to assess their contribution to the maintenance of the anatomical integrity of multicellular organisms. As a model, we selected the glyconectin 1, a cell adhesion proteoglycan isolated from the marine sponge Microciona prolifera. This glyconectin mediates in vivo cell recognition and aggregation via homophilic, species-specific, polyvalent, and calcium ion-dependent carbohydrate-carbohydrate interactions. Under physiological conditions, an adhesive force of up to 400 piconewtons

  5. 47 CFR 22.901 - Cellular service requirements and limitations.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cellular service requirements and limitations... SERVICES PUBLIC MOBILE SERVICES Cellular Radiotelephone Service § 22.901 Cellular service requirements and limitations. The licensee of each cellular system is responsible for ensuring that its cellular system...

  6. Green Virtualization for Multiple Collaborative Cellular Operators

    KAUST Repository

    Farooq, Muhammad Junaid; Ghazzai, Hakim; Yaacoub, Elias; Kadri, Abdullah; Alouini, Mohamed-Slim

    2017-01-01

    This paper proposes and investigates a green virtualization framework for infrastructure sharing among multiple cellular operators whose networks are powered by a combination of conventional and renewable sources of energy. Under the proposed

  7. Corrosion of Cellular Metals in Marine Environments

    National Research Council Canada - National Science Library

    Scully, John R

    2006-01-01

    .... The basis for this work is an interdisciplinary approach that aims to understand: (a) the electrochemical, chemical, and metallurgical conditions that corrode cellular metals in marine environments when fabricated by brazing processes, (b...

  8. A cryptosystem based on elementary cellular automata

    Science.gov (United States)

    Abdo, A. A.; Lian, Shiguo; Ismail, I. A.; Amin, M.; Diab, H.

    2013-01-01

    Based on elementary cellular automata, a new image encryption algorithm is proposed in this paper. In this algorithm, a special kind of periodic boundary cellular automata with unity attractors is used. From the viewpoint of security, the number of cellular automata attractor states are changed with respect to the encrypted image, and different key streams are used to encrypt different plain images. The cellular neural network with chaotic properties is used as the generator of a pseudo-random key stream. Theoretical analysis and experimental results have both confirmed that the proposed algorithm possesses high security level and good performances against differential and statistical attacks. The comparison with other existing schemes is given, which shows the superiority of the proposal scheme.

  9. Mapping crime scenes and cellular telephone usage

    CSIR Research Space (South Africa)

    Schmitz, Peter MU

    2000-12-01

    Full Text Available This paper describes a method that uses a desktop geographical information system (GIS) to plot cellular telephone conversations made when crimes are committed, such as hijackings, hostage taking, kidnapping, rape and murder. The maps produced...

  10. Recent development of cellular manufacturing systems

    Indian Academy of Sciences (India)

    be manufactured in a cell, and the machines, which will comprise that cell, can be ... approaches for the CF problem which is referred to as Production Flow Analysis (PFA). ... programming model of cellular manufacturing system design which ...

  11. Cellular strategies to cope with protein aggregation

    NARCIS (Netherlands)

    Scior, Annika; Juenemann, Katrin; Kirstein, Janine

    2016-01-01

    Nature has evolved several mechanisms to detoxify intracellular protein aggregates that arise upon proteotoxic challenges. These include the controlled deposition of misfolded proteins at distinct cellular sites, the protein disaggregation and refolding by molecular chaperones and/or degradation of

  12. Cellular Reprogramming–Turning the Clock Back

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 6. Cellular Reprogramming - Turning the Clock Back - Nobel Prize in Physiology or Medicine, 2012. Deepa Subramanyam. General Article Volume 18 Issue 6 June 2013 pp 514-521 ...

  13. Dynamic cellular manufacturing system design considering ...

    Indian Academy of Sciences (India)

    Kamal Deep

    cellular manufacturing system in a company is division of ... designed to be assembled from a small number of stan- ..... contingency part process route in addition to the alternate .... istic industrial manufacturing vision considering multiple.

  14. Probing Cellular Dynamics with Mesoscopic Simulations

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2010-01-01

    Cellular processes span a huge range of length and time scales from the molecular to the near-macroscopic. Understanding how effects on one scale influence, and are themselves influenced by, those on lower and higher scales is a critical issue for the construction of models in Systems Biology....... Advances in computing hardware and software now allow explicit simulation of some aspects of cellular dynamics close to the molecular scale. Vesicle fusion is one example of such a process. Experiments, however, typically probe cellular behavior from the molecular scale up to microns. Standard particle...... soon be coupled to Mass Action models allowing the parameters in such models to be continuously tuned according to the finer resolution simulation. This will help realize the goal of a computational cellular simulation that is able to capture the dynamics of membrane-associated processes...

  15. Cellular telephone use and cancer risk

    DEFF Research Database (Denmark)

    Schüz, Joachim; Jacobsen, Rune; Olsen, Jørgen H.

    2006-01-01

    BACKGROUND: The widespread use of cellular telephones has heightened concerns about possible adverse health effects. The objective of this study was to investigate cancer risk among Danish cellular telephone users who were followed for up to 21 years. METHODS: This study is an extended follow......-up of a large nationwide cohort of 420,095 persons whose first cellular telephone subscription was between 1982 and 1995 and who were followed through 2002 for cancer incidence. Standardized incidence ratios (SIRs) were calculated by dividing the number of observed cancer cases in the cohort by the number...... expected in the Danish population. RESULTS: A total of 14,249 cancers were observed (SIR = 0.95; 95% confidence interval [CI] = 0.93 to 0.97) for men and women combined. Cellular telephone use was not associated with increased risk for brain tumors (SIR = 0.97), acoustic neuromas (SIR = 0.73), salivary...

  16. Cellular Phone Users- Willingness to Shop Online

    OpenAIRE

    Norazah Mohd Suki; Norbayah Mohd Suki

    2009-01-01

    This study aims to identify cellular phone users- shopping motivating factors towards online shopping. 100 university students located in Klang Valley, Malaysia were involved as the respondents. They were required to complete a set of questionnaire and had to own a cellular phone in order to be selected as sample in this study. Three from five proposed hypotheses were supported: purchasing information, shopping utilities and service quality. As a result, marketers and retailers should concent...

  17. Shape Memory Alloy-Based Periodic Cellular Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort will develop and demonstrate an innovative shape memory alloy (SMA) periodic cellular structural technology. Periodic cellular structures...

  18. Characterizing heterogeneous cellular responses to perturbations.

    Science.gov (United States)

    Slack, Michael D; Martinez, Elisabeth D; Wu, Lani F; Altschuler, Steven J

    2008-12-09

    Cellular populations have been widely observed to respond heterogeneously to perturbation. However, interpreting the observed heterogeneity is an extremely challenging problem because of the complexity of possible cellular phenotypes, the large dimension of potential perturbations, and the lack of methods for separating meaningful biological information from noise. Here, we develop an image-based approach to characterize cellular phenotypes based on patterns of signaling marker colocalization. Heterogeneous cellular populations are characterized as mixtures of phenotypically distinct subpopulations, and responses to perturbations are summarized succinctly as probabilistic redistributions of these mixtures. We apply our method to characterize the heterogeneous responses of cancer cells to a panel of drugs. We find that cells treated with drugs of (dis-)similar mechanism exhibit (dis-)similar patterns of heterogeneity. Despite the observed phenotypic diversity of cells observed within our data, low-complexity models of heterogeneity were sufficient to distinguish most classes of drug mechanism. Our approach offers a computational framework for assessing the complexity of cellular heterogeneity, investigating the degree to which perturbations induce redistributions of a limited, but nontrivial, repertoire of underlying states and revealing functional significance contained within distinct patterns of heterogeneous responses.

  19. Cellular automatons applied to gas dynamic problems

    Science.gov (United States)

    Long, Lyle N.; Coopersmith, Robert M.; Mclachlan, B. G.

    1987-01-01

    This paper compares the results of a relatively new computational fluid dynamics method, cellular automatons, with experimental data and analytical results. This technique has been shown to qualitatively predict fluidlike behavior; however, there have been few published comparisons with experiment or other theories. Comparisons are made for a one-dimensional supersonic piston problem, Stokes first problem, and the flow past a normal flat plate. These comparisons are used to assess the ability of the method to accurately model fluid dynamic behavior and to point out its limitations. Reasonable results were obtained for all three test cases, but the fundamental limitations of cellular automatons are numerous. It may be misleading, at this time, to say that cellular automatons are a computationally efficient technique. Other methods, based on continuum or kinetic theory, would also be very efficient if as little of the physics were included.

  20. Alleviate Cellular Congestion Through Opportunistic Trough Filling

    Directory of Open Access Journals (Sweden)

    Yichuan Wang

    2014-04-01

    Full Text Available The demand for cellular data service has been skyrocketing since the debut of data-intensive smart phones and touchpads. However, not all data are created equal. Many popular applications on mobile devices, such as email synchronization and social network updates, are delay tolerant. In addition, cellular load varies significantly in both large and small time scales. To alleviate network congestion and improve network performance, we present a set of opportunistic trough filling schemes that leverage the time-variation of network congestion and delay-tolerance of certain traffic in this paper. We consider average delay, deadline, and clearance time as the performance metrics. Simulation results show promising performance improvement over the standard schemes. The work shed lights on addressing the pressing issue of cellular overload.

  1. Cellular Signaling in Health and Disease

    CERN Document Server

    Beckerman, Martin

    2009-01-01

    In today’s world, three great classes of non-infectious diseases – the metabolic syndromes (such as type 2 diabetes and atherosclerosis), the cancers, and the neurodegenerative disorders – have risen to the fore. These diseases, all associated with increasing age of an individual, have proven to be remarkably complex and difficult to treat. This is because, in large measure, when the cellular signaling pathways responsible for maintaining homeostasis and health of the body become dysregulated, they generate equally stable disease states. As a result the body may respond positively to a drug, but only for a while and then revert back to the disease state. Cellular Signaling in Health and Disease summarizes our current understanding of these regulatory networks in the healthy and diseased states, showing which molecular components might be prime targets for drug interventions. This is accomplished by presenting models that explain in mechanistic, molecular detail how a particular part of the cellular sign...

  2. Passive Noise Filtering by Cellular Compartmentalization.

    Science.gov (United States)

    Stoeger, Thomas; Battich, Nico; Pelkmans, Lucas

    2016-03-10

    Chemical reactions contain an inherent element of randomness, which presents itself as noise that interferes with cellular processes and communication. Here we discuss the ability of the spatial partitioning of molecular systems to filter and, thus, remove noise, while preserving regulated and predictable differences between single living cells. In contrast to active noise filtering by network motifs, cellular compartmentalization is highly effective and easily scales to numerous systems without requiring a substantial usage of cellular energy. We will use passive noise filtering by the eukaryotic cell nucleus as an example of how this increases predictability of transcriptional output, with possible implications for the evolution of complex multicellularity. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Cellular-automata method for phase unwrapping

    International Nuclear Information System (INIS)

    Ghiglia, D.C.; Mastin, G.A.; Romero, L.A.

    1987-01-01

    Research into two-dimensional phase unwrapping has uncovered interesting and troublesome inconsistencies that cause path-dependent results. Cellular automata, which are simple, discrete mathematical systems, offered promise of computation in nondirectional, parallel manner. A cellular automaton was discovered that can unwrap consistent phase data in n dimensions in a path-independent manner and can automatically accommodate noise-induced (pointlike) inconsistencies and arbitrary boundary conditions (region partitioning). For data with regional (nonpointlike) inconsistencies, no phase-unwrapping algorithm will converge, including the cellular-automata approach. However, the automata method permits more simple visualization of the regional inconsistencies. Examples of its behavior on one- and two-dimensional data are presented

  4. Cyclic cellular automata in 3D

    International Nuclear Information System (INIS)

    Reiter, Clifford A.

    2011-01-01

    Highlights: → We explore the self-organization of cyclic cellular automata in 3D. → Von Neumann, Moore and two types of intermediate neighborhoods are investigated. → Random neighborhoods self organize through phases into complex nested structures. → Demons are seen to have many alternatives in 3D. - Abstract: Cyclic cellular automata in two dimensions have long been intriguing because they self organize into spirals and that behavior can be analyzed. The form for the patterns that develop is highly dependent upon the form of the neighborhood. We extend this work to three dimensional cyclic cellular automata and observe self organization dependent upon the neighborhood type. This includes neighborhood types intermediate between Von Neumann and Moore neighborhoods. We also observe that the patterns include nested shells with the appropriate forms but that the nesting is far more complex than the spirals that occur in two dimensions.

  5. VUV spectroscopy of water under cellular conditions

    International Nuclear Information System (INIS)

    Mota, R.; Parafita, R.; Maneira, M. J. P.; Mason, N. J.; Garcia, G.; Ribeiro, P. A.; Raposo, M.; Limao-Vieira, P.

    2006-01-01

    The understanding of radiation damage within cells, and thence mutagenesis, depends upon a detailed knowledge of the spectroscopy and dissociation dynamics of water. Results of a new study of the electronic state spectroscopy of water, using synchrotron radiation are reported. In order to gain some insight into how the spectroscopy and dissociation dynamics of water is influenced by its environment we also report photo-absorption spectra of water within thin films of poly(o-methoxyaniline) which have been suggested as a good mimic for biological membranes in the cellular environment. Comparison of these spectra with those of gaseous water and condensed amorphous water ice suggest that water in such films is similar to gaseous water and does not show the blue shift suggested in some cellular models. The lowest energy of OH production from dissociation of water in the cellular environment may therefore be around 6.7 eV (185 nm). (authors)

  6. Cellular Stress Response to Engineered Nanoparticles: Effect of Size, Surface Coating, and Cellular Uptake

    Science.gov (United States)

    CELLULAR STRESS RESPONSE TO ENGINEERED NANOPARTICLES: EFFECT OF SIZE, SURFACE COATING, AND CELLULAR UPTAKE RY Prasad 1, JK McGee2, MG Killius1 D Ackerman2, CF Blackman2 DM DeMarini2 , SO Simmons2 1 Student Services Contractor, US EPA, RTP, NC 2 US EPA, RTP, NC The num...

  7. Genomic stability during cellular reprogramming: Mission impossible?

    Energy Technology Data Exchange (ETDEWEB)

    Joest, Mathieu von; Búa Aguín, Sabela; Li, Han, E-mail: han.li@pasteur.fr

    2016-06-15

    The generation of induced pluripotent stem cells (iPSCs) from adult somatic cells is one of the most exciting discoveries in recent biomedical research. It holds tremendous potential in drug discovery and regenerative medicine. However, a series of reports highlighting genomic instability in iPSCs raises concerns about their clinical application. Although the mechanisms cause genomic instability during cellular reprogramming are largely unknown, several potential sources have been suggested. This review summarizes current knowledge on this active research field and discusses the latest efforts to alleviate the genomic insults during cellular reprogramming to generate iPSCs with enhanced quality and safety.

  8. Toxicology and cellular effect of manufactured nanomaterials

    Science.gov (United States)

    Chen, Fanqing

    2014-07-22

    The increasing use of nanotechnology in consumer products and medical applications underlies the importance of understanding its potential toxic effects to people and the environment. Herein are described methods and assays to predict and evaluate the cellular effects of nanomaterial exposure. Exposing cells to nanomaterials at cytotoxic doses induces cell cycle arrest and increases apoptosis/necrosis, activates genes involved in cellular transport, metabolism, cell cycle regulation, and stress response. Certain nanomaterials induce genes indicative of a strong immune and inflammatory response within skin fibroblasts. Furthermore, the described multiwall carbon nanoonions (MWCNOs) can be used as a therapeutic in the treatment of cancer due to its cytotoxicity.

  9. Capacity on wireless quantum cellular communication system

    Science.gov (United States)

    Zhou, Xiang-Zhen; Yu, Xu-Tao; Zhang, Zai-Chen

    2018-03-01

    Quantum technology is making excellent prospects in future communication networks. Entanglement generation and purification are two major components in quantum networks. Combining these two techniques with classical cellular mobile communication, we proposed a novel wireless quantum cellular(WQC) communication system which is possible to realize commercial mobile quantum communication. In this paper, the architecture and network topology of WQC communication system are discussed, the mathematical model of WQC system is extracted and the serving capacity, indicating the ability to serve customers, is defined and calculated under certain circumstances.

  10. Retroperitoneal Cellular Angiofibroma: A Rare Gynecological Entity

    Directory of Open Access Journals (Sweden)

    Ana Brandão

    2017-12-01

    Full Text Available Cellular angiofibroma is a mesenchymal tumor, described in 1997, without gender preference, that usually appears at age 40. The vulvovaginal area is the most common site in women, mimicking vulvar benign tumors, like Bartholin gland cyst. However, there are a few described cases of a deep or extra-pelvic angiofibroma. Excision is the treatment of choice and the recurrence rate appears to be low. We present the case of a woman with a heterogeneous tumor in the right adnexial region. At the surgery, a retroperitoneal tumor was excised and the histopathological tissue analysis revealed a cellular angiofibroma.

  11. External insulation with cellular plastic materials

    DEFF Research Database (Denmark)

    Sørensen, Lars Schiøtt; Nielsen, Anker

    2014-01-01

    External thermal insulation composite systems (ETICS) can be used as extra insulation of existing buildings. The system can be made of cellular plastic materials or mineral wool. There is a European Technical guideline, ETAG 004, that describe the tests that shall be conducted on such systems....... This paper gives a comparison of systems with mineral wool and cellular plastic, based on experience from practice and literature. It is important to look at the details in the system and at long time stability of the properties such as thermal insulation, moisture and fire. Investigation of fire properties...

  12. Algorithmic crystal chemistry: A cellular automata approach

    International Nuclear Information System (INIS)

    Krivovichev, S. V.

    2012-01-01

    Atomic-molecular mechanisms of crystal growth can be modeled based on crystallochemical information using cellular automata (a particular case of finite deterministic automata). In particular, the formation of heteropolyhedral layered complexes in uranyl selenates can be modeled applying a one-dimensional three-colored cellular automaton. The use of the theory of calculations (in particular, the theory of automata) in crystallography allows one to interpret crystal growth as a computational process (the realization of an algorithm or program with a finite number of steps).

  13. Chaotic behavior in the disorder cellular automata

    International Nuclear Information System (INIS)

    Ko, J.-Y.; Hung, Y.-C.; Ho, M.-C.; Jiang, I-M.

    2008-01-01

    Disordered cellular automata (DCA) represent an intermediate class between elementary cellular automata and the Kauffman network. Recently, Rule 126 of DCA has been explicated: the system can be accurately described by a discrete probability function. However, a means of extending to other rules has not been developed. In this investigation, a density map of the dynamical behavior of DCA is formulated based on Rule 22 and other totalistic rules. The numerical results reveal excellent agreement between the model and original automata. Furthermore, the inhomogeneous situation is also discussed

  14. Cellular Automata Simulation for Wealth Distribution

    Science.gov (United States)

    Lo, Shih-Ching

    2009-08-01

    Wealth distribution of a country is a complicate system. A model, which is based on the Epstein & Axtell's "Sugars cape" model, is presented in Netlogo. The model considers the income, age, working opportunity and salary as control variables. There are still other variables should be considered while an artificial society is established. In this study, a more complicate cellular automata model for wealth distribution model is proposed. The effects of social welfare, tax, economical investment and inheritance are considered and simulated. According to the cellular automata simulation for wealth distribution, we will have a deep insight of financial policy of the government.

  15. 47 CFR 22.923 - Cellular system configuration.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cellular system configuration. 22.923 Section... MOBILE SERVICES Cellular Radiotelephone Service § 22.923 Cellular system configuration. Mobile stations... directly or through cellular repeaters. Auxiliary test stations may communicate with base or mobile...

  16. 47 CFR 22.905 - Channels for cellular service.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Channels for cellular service. 22.905 Section... MOBILE SERVICES Cellular Radiotelephone Service § 22.905 Channels for cellular service. The following frequency bands are allocated for assignment to service providers in the Cellular Radiotelephone Service. (a...

  17. A cellular automata model for ant trails

    Indian Academy of Sciences (India)

    In this study, the unidirectional ant traffic flow with U-turn in an ant trail was investigated using one-dimensional cellular automata model. It is known that ants communicate with each other by dropping a chemical, called pheromone, on the substrate. Apart from the studies in the literature, it was considered in the model that ...

  18. Adaptive downtilt for cellular base stations

    NARCIS (Netherlands)

    Mestrom, R.M.C.; Coenen, T.J.; Smolders, A.B.

    2012-01-01

    Efficiency, reconfigurability, and power consumption are paramount for future communication systems in applications such as cellular handsets, base stations and home networking systems. We present our work in the European PANAMA project which addresses the associated challenges. Our work focuses on

  19. Biochemical Factors Modulating Cellular Neurotoxicity of Methylmercury

    Directory of Open Access Journals (Sweden)

    Parvinder Kaur

    2011-01-01

    Full Text Available Methylmercury (MeHg, an environmental toxicant primarily found in fish and seafood, poses a dilemma to both consumers and regulatory authorities, given the nutritional benefits of fish consumption versus the possible adverse neurological damage. Several studies have shown that MeHg toxicity is influenced by a number of biochemical factors, such as glutathione (GSH, fatty acids, vitamins, and essential elements, but the cellular mechanisms underlying these complex interactions have not yet been fully elucidated. The objective of this paper is to outline the cellular response to dietary nutrients, as well as to describe the neurotoxic exposures to MeHg. In order to determine the cellular mechanism(s of toxicity, the effect of pretreatment with biochemical factors (e.g., N-acetyl cysteine, (NAC; diethyl maleate, (DEM; docosahexaenoic acid, (DHA; selenomethionine, SeM; Trolox and MeHg treatment on intercellular antioxidant status, MeHg content, and other endpoints was evaluated. This paper emphasizes that the protection against oxidative stress offered by these biochemical factors is among one of the major mechanisms responsible for conferring neuroprotection. It is therefore critical to ascertain the cellular mechanisms associated with various dietary nutrients as well as to determine the potential effects of neurotoxic exposures for accurately assessing the risks and benefits associated with fish consumption.

  20. Terminal addition in a cellular world.

    Science.gov (United States)

    Torday, J S; Miller, William B

    2018-07-01

    Recent advances in our understanding of evolutionary development permit a reframed appraisal of Terminal Addition as a continuous historical process of cellular-environmental complementarity. Within this frame of reference, evolutionary terminal additions can be identified as environmental induction of episodic adjustments to cell-cell signaling patterns that yield the cellular-molecular pathways that lead to differing developmental forms. Phenotypes derive, thereby, through cellular mutualistic/competitive niche constructions in reciprocating responsiveness to environmental stresses and epigenetic impacts. In such terms, Terminal Addition flows according to a logic of cellular needs confronting environmental challenges over space-time. A reconciliation of evolutionary development and Terminal Addition can be achieved through a combined focus on cell-cell signaling, molecular phylogenies and a broader understanding of epigenetic phenomena among eukaryotic organisms. When understood in this manner, Terminal Addition has an important role in evolutionary development, and chronic disease might be considered as a form of 'reverse evolution' of the self-same processes. Copyright © 2017. Published by Elsevier Ltd.

  1. Overview of cellular automaton models for corrosion

    International Nuclear Information System (INIS)

    Perez-Brokate, Cristian Felipe; De Lamare, Jacques; Dung di Caprio; Feron, Damien; Chausse, Annie

    2014-01-01

    A review of corrosion process modeling using cellular automata methods is presented. This relatively new and growing approach takes into account the stochastic nature of the phenomena and uses physico-chemical rules to make predictions at a mesoscopic scale. Milestone models are analyzed and perspectives are established. (authors)

  2. The cellular basis of organ ageing

    NARCIS (Netherlands)

    Knook, D.L.

    1978-01-01

    Ageing is associated with declines in the functional capacities of several organs. General causes for the decline can be divided into: 1. intrinsic cellular causes and 2. extracellular causes, e.g., changes in blood circulation and distribution. For the first group of causes, there is evidence for a

  3. Cellular automata machines as physics emulators

    International Nuclear Information System (INIS)

    Toffoli, T.

    1988-01-01

    Can one design a computer optimized to be a physics emulator rather than a software interpreter? Cellular automata are discrete dynamical systems whose behavior is completely specified in terms of a local relation, much as is the case for a large class of continuous dynamical systems defined by partial differential equations. 31 refs, 3 figs

  4. Cellular modeling of fault-tolerant multicomputers

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, G

    1987-01-01

    Work described was concerned with a novel method for investigation of fault tolerance in large regular networks of computers. Motivation was to provide a technique useful in rapid evaluation of highly reliable systems that exploit the low cost and ease of volume production of simple microcomputer components. First, a system model and simulator based upon cellular automata are developed. This model is characterized by its simplicity and ease of modification when adapting to new types of network. Second, in order to test and verify the predictive capabilities of the cellular system, a more-detailed simulation is performed based upon an existing computational model, that of the Transputer. An example application is used to exercise various systems designed using the cellular model. Using this simulator, experimental results are obtained both for existing well-understood configurations and for more novel types also developed here. In all cases it was found that the cellular model and simulator successfully predicted the ranking in reliability improvement of the systems studied.

  5. Fuzzy cellular automata models in immunology

    International Nuclear Information System (INIS)

    Ahmed, E.

    1996-01-01

    The self-nonself character of antigens is considered to be fuzzy. The Chowdhury et al. cellular automata model is generalized accordingly. New steady states are found. The first corresponds to a below-normal help and suppression and is proposed to be related to autoimmune diseases. The second corresponds to a below-normal B-cell level

  6. Gravitational Effects on Cellular Flame Structure

    Science.gov (United States)

    Dunsky, C. M.; Fernandez-Pello, A. C.

    1991-01-01

    An experimental investigation has been conducted of the effect of gravity on the structure of downwardly propagating, cellular premixed propane-oxygen-nitrogen flames anchored on a water-cooled porous-plug burner. The flame is subjected to microgravity conditions in the NASA Lewis 2.2-second drop tower, and flame characteristics are recorded on high-speed film. These are compared to flames at normal gravity conditions with the same equivalence ratio, dilution index, mixture flow rate, and ambient pressure. The results show that the cellular instability band, which is located in the rich mixture region, changes little under the absence of gravity. Lifted normal-gravity flames near the cellular/lifted limits, however, are observed to become cellular when gravity is reduced. Observations of a transient cell growth period following ignition point to heat loss as being an important mechanism in the overall flame stability, dominating the stabilizing effect of buoyancy for these downwardly-propagating burner-anchored flames. The pulsations that are observed in the plume and diffusion flame generated downstream of the premixed flame in the fuel rich cases disappear in microgravity, verifying that these fluctuations are gravity related.

  7. Cellular Automata Rules and Linear Numbers

    OpenAIRE

    Nayak, Birendra Kumar; Sahoo, Sudhakar; Biswal, Sagarika

    2012-01-01

    In this paper, linear Cellular Automta (CA) rules are recursively generated using a binary tree rooted at "0". Some mathematical results on linear as well as non-linear CA rules are derived. Integers associated with linear CA rules are defined as linear numbers and the properties of these linear numbers are studied.

  8. Cellular Restriction Factors of Feline Immunodeficiency Virus

    Directory of Open Access Journals (Sweden)

    Carsten Münk

    2011-10-01

    Full Text Available Lentiviruses are known for their narrow cell- and species-tropisms, which are determined by cellular proteins whose absence or presence either support viral replication (dependency factors, cofactors or inhibit viral replication (restriction factors. Similar to Human immunodeficiency virus type 1 (HIV-1, the cat lentivirus Feline immunodeficiency virus (FIV is sensitive to recently discovered cellular restriction factors from non-host species that are able to stop viruses from replicating. Of particular importance are the cellular proteins APOBEC3, TRIM5α and tetherin/BST-2. In general, lentiviruses counteract or escape their species’ own variant of the restriction factor, but are targeted by the orthologous proteins of distantly related species. Most of the knowledge regarding lentiviral restriction factors has been obtained in the HIV-1 system; however, much less is known about their effects on other lentiviruses. We describe here the molecular mechanisms that explain how FIV maintains its replication in feline cells, but is largely prevented from cross-species infections by cellular restriction factors.

  9. Cellular Restriction Factors of Feline Immunodeficiency Virus

    Science.gov (United States)

    Zielonka, Jörg; Münk, Carsten

    2011-01-01

    Lentiviruses are known for their narrow cell- and species-tropisms, which are determined by cellular proteins whose absence or presence either support viral replication (dependency factors, cofactors) or inhibit viral replication (restriction factors). Similar to Human immunodeficiency virus type 1 (HIV-1), the cat lentivirus Feline immunodeficiency virus (FIV) is sensitive to recently discovered cellular restriction factors from non-host species that are able to stop viruses from replicating. Of particular importance are the cellular proteins APOBEC3, TRIM5α and tetherin/BST-2. In general, lentiviruses counteract or escape their species’ own variant of the restriction factor, but are targeted by the orthologous proteins of distantly related species. Most of the knowledge regarding lentiviral restriction factors has been obtained in the HIV-1 system; however, much less is known about their effects on other lentiviruses. We describe here the molecular mechanisms that explain how FIV maintains its replication in feline cells, but is largely prevented from cross-species infections by cellular restriction factors. PMID:22069525

  10. Cellular grafts in management of leucoderma

    Directory of Open Access Journals (Sweden)

    Mysore Venkataram

    2009-01-01

    Full Text Available Cellular grafting methods constitute important advances in the surgical management of leucoderma. Different methods such as noncultured epidermal suspensions, melanocyte cultures, and melanocyte-keratinocyte cultures have all been shown to be effective. This article reviews these methods.

  11. Power load balancing in cellular networks

    NARCIS (Netherlands)

    2010-01-01

    In one aspect, a system is provided. In one embodiment, the system includes a plurality of wireless base stations that are located in a contiguous spatial coverage region of a cellular communication system. Each wireless base station that is configured to generate a coverage pilot beam to enable

  12. Their function on angiogenesis and cellular signalling

    Indian Academy of Sciences (India)

    Copper, although known as a micronutrient, has a pivotal role in modulating the cellular metabolism. Many studieshave reported the role of copper in angiogenesis. Copper chaperones are intracellular proteins that mediate coppertrafficking to various cell organelles. However, the role and function of copper chaperones in ...

  13. Cellular biomarker responses of bagrid catfish, Chrysichthys ...

    African Journals Online (AJOL)

    An assessment of the pollution status of Agboyi creek, a water body associated with various anthropogenic activities was carried out in order to determine responses induced in Catfishes, Chrysichthys nigrodigitatus inhabiting it. Cellular biomarkers of stress including the antioxidative stress enzyme, catalase (CAT), lipid ...

  14. Designing cellular manufacturing system under risk conditions ...

    African Journals Online (AJOL)

    This paper develops a mathematical modeling to design a cellular manufacturing system. In addition some of the total or portion of the demand of the part types can be subcontracted.. In order to designing the optimal CMS, we needs to detrmined a plan to produce and subcontract parts at a minimum cost and to mitigate the ...

  15. Building mathematics cellular phone learning communities

    Directory of Open Access Journals (Sweden)

    Wajeeh M. Daher

    2011-04-01

    Full Text Available Researchers emphasize the importance of maintaining learning communities and environments. This article describes the building and nourishment of a learning community, one comprised of middle school students who learned mathematics out-of-class using the cellular phone. The building of the learning community was led by three third year pre-service teachers majoring in mathematics and computers. The pre-service teachers selected thirty 8th grade students to learn mathematics with the cellular phone and be part of a learning community experimenting with this learning. To analyze the building and development stages of the cellular phone learning community, two models of community building stages were used; first the team development model developed by Tuckman (1965, second the life cycle model of a virtual learning community developed by Garber (2004. The research findings indicate that a learning community which is centered on a new technology has five 'life' phases of development: Pre-birth, birth, formation, performing, and maturity. Further, the research finding indicate that the norms that were encouraged by the preservice teachers who initiated the cellular phone learning community resulted in a community which developed, nourished and matured to be similar to a community of experienced applied mathematicians who use mathematical formulae to study everyday phenomena.

  16. Predicting cellular growth from gene expression signatures.

    Directory of Open Access Journals (Sweden)

    Edoardo M Airoldi

    2009-01-01

    Full Text Available Maintaining balanced growth in a changing environment is a fundamental systems-level challenge for cellular physiology, particularly in microorganisms. While the complete set of regulatory and functional pathways supporting growth and cellular proliferation are not yet known, portions of them are well understood. In particular, cellular proliferation is governed by mechanisms that are highly conserved from unicellular to multicellular organisms, and the disruption of these processes in metazoans is a major factor in the development of cancer. In this paper, we develop statistical methodology to identify quantitative aspects of the regulatory mechanisms underlying cellular proliferation in Saccharomyces cerevisiae. We find that the expression levels of a small set of genes can be exploited to predict the instantaneous growth rate of any cellular culture with high accuracy. The predictions obtained in this fashion are robust to changing biological conditions, experimental methods, and technological platforms. The proposed model is also effective in predicting growth rates for the related yeast Saccharomyces bayanus and the highly diverged yeast Schizosaccharomyces pombe, suggesting that the underlying regulatory signature is conserved across a wide range of unicellular evolution. We investigate the biological significance of the gene expression signature that the predictions are based upon from multiple perspectives: by perturbing the regulatory network through the Ras/PKA pathway, observing strong upregulation of growth rate even in the absence of appropriate nutrients, and discovering putative transcription factor binding sites, observing enrichment in growth-correlated genes. More broadly, the proposed methodology enables biological insights about growth at an instantaneous time scale, inaccessible by direct experimental methods. Data and tools enabling others to apply our methods are available at http://function.princeton.edu/growthrate.

  17. Cellular glutathione prevents cytolethality of monomethylarsonic acid

    International Nuclear Information System (INIS)

    Sakurai, Teruaki; Kojima, Chikara; Ochiai, Masayuki; Ohta, Takami; Sakurai, Masumi H.; Waalkes, Michael P.; Fujiwara, Kitao

    2004-01-01

    Inorganic arsenicals are clearly toxicants and carcinogens in humans. In mammals, including humans, inorganic arsenic often undergoes methylation, forming compounds such as monomethylarsonic acid (MMAs V ) and dimethylarsinic acid (DMAs V ). However, much less information is available on the in vitro toxic potential or mechanisms of these methylated arsenicals, especially MMAs V . We studied the molecular mechanisms of in vitro cytolethality of MMAs V using a rat liver epithelial cell line (TRL 1215). MMAs V was not cytotoxic in TRL 1215 cells even at concentrations exceeding 10 mM, but it became weakly cytotoxic and induced both necrotic and apoptotic cell death when cellular reduced glutathione (GSH) was depleted with the glutathione synthase inhibitor, L-buthionine-[S,R]-sulfoximine (BSO), or the glutathione reductase inhibitor, carmustine. Similar results were observed in the other mammalian cells, such as human skin TIG-112 cells, chimpanzee skin CRT-1609 cells, and mouse metallothionein (MT) positive and MT negative embryonic cells. Ethacrynic acid (EA), an inhibitor of glutathione S-transferase (GST) that catalyses GSH-substrate conjugation, also enhanced the cytolethality of MMAs V , but aminooxyacetic acid (AOAA), an inhibitor of β-lyase that catalyses the final breakdown of GSH-substrate conjugates, had no effect. Both the cellular GSH levels and the cellular GST activity were increased by the exposure to MMAs V in TRL 1215 cells. On the other hand, the addition of exogenous extracellular GSH enhanced the cytolethality of MMAs V , although cellular GSH levels actually prevented the cytolethality of combined MMAs V and exogenous GSH. These findings indicate that human arsenic metabolite MMAs V is not a highly toxic compound in mammalian cells, and the level of cellular GSH is critical to its eventual toxic effects

  18. Cellular dosimetry in nuclear medicine imaging: training

    International Nuclear Information System (INIS)

    Gardin, I.; Faraggi, M.; Stievenart, J.L.; Le Guludec, D.; Bok, B.

    1998-01-01

    The radionuclides used in nuclear medicine imaging emit not only diagnostically useful photons, but also energy electron emissions, responsible for dose heterogeneity at the cellular level. The mean dose delivered to the cell nucleus by electron emissions of 99m Tc, 123 I, 111 In, 67 Ga, and 201 Tl, has been calculated, for the cell nucleus, a cytoplasmic and a cell membrane distribution of radioactivity. This model takes into account both the self-dose which results from the radionuclide located in the target cell, and the cross-dose, which comes from the surrounding cells. The results obtained by cellular dosimetry (D cel ) have been compared with those obtained with conventional dosimetry (D conv ), by assuming the same amount of radioactivity per cell. Cellular dosimetry shows, for a cytoplasmic and a cell membrane distributions of radioactivity, that the main contribution to the dose to the cell nucleus, comes from the surrounding cells. On the other hand, for a cell nucleus distribution of radioactivity, the self-dose is not negligible and may be the main contribution. The comparison between cellular and conventional dosimetry shows that D cel /D conv ratio ranges from 0.61 and O.89, in case of a cytoplasmic and a cell membrane distributions of radioactivity, depending on the radionuclide and cell dimensions. Thus, conventional dosimetry slightly overestimates the mean dose to the cell nucleus. On the other hand, D cel /D conv ranges from 1.1 to 75, in case of a cell nucleus distribution of radioactivity. Conventional dosimetry may strongly underestimates the absorbed dose to the nucleus, when radioactivity is located in the nucleus. The study indicates that in nuclear medicine imaging, cellular dosimetry may lead to a better understanding of biological effects of radiopharmaceuticals. (authors)

  19. Induction of cellular transformation by irradiation from artificial light sources

    International Nuclear Information System (INIS)

    Withrow, T.J.

    1981-01-01

    Cellular transformation in vitro has been used to test for the carcinogenic potential of chemical and physical insults including light. This report discusses the measurement of transformation, and reviews studies done on the effects of exposure to artificial light on cellular transformation or on cellular transformation by a virus. To date, cool-white lamps have been found to cause cellular transformation, while germicidal lamps and sunlamps have been found to cause cellular transformation and to enhance virally produced transformation

  20. Modeling the mechanics of cancer: effect of changes in cellular and extra-cellular mechanical properties.

    Science.gov (United States)

    Katira, Parag; Bonnecaze, Roger T; Zaman, Muhammad H

    2013-01-01

    Malignant transformation, though primarily driven by genetic mutations in cells, is also accompanied by specific changes in cellular and extra-cellular mechanical properties such as stiffness and adhesivity. As the transformed cells grow into tumors, they interact with their surroundings via physical contacts and the application of forces. These forces can lead to changes in the mechanical regulation of cell fate based on the mechanical properties of the cells and their surrounding environment. A comprehensive understanding of cancer progression requires the study of how specific changes in mechanical properties influences collective cell behavior during tumor growth and metastasis. Here we review some key results from computational models describing the effect of changes in cellular and extra-cellular mechanical properties and identify mechanistic pathways for cancer progression that can be targeted for the prediction, treatment, and prevention of cancer.

  1. Designing beauty the art of cellular automata

    CERN Document Server

    Martínez, Genaro

    2016-01-01

    This fascinating, colourful book offers in-depth insights and first-hand working experiences in the production of art works, using simple computational models with rich morphological behaviour, at the edge of mathematics, computer science, physics and biology. It organically combines ground breaking scientific discoveries in the theory of computation and complex systems with artistic representations of the research results. In this appealing book mathematicians, computer scientists, physicists, and engineers brought together marvelous and esoteric patterns generated by cellular automata, which are arrays of simple machines with complex behavior. Configurations produced by cellular automata uncover mechanics of dynamic patterns formation, their propagation and interaction in natural systems: heart pacemaker, bacterial membrane proteins, chemical rectors, water permeation in soil, compressed gas, cell division, population dynamics, reaction-diffusion media and self-organisation. The book inspires artists to tak...

  2. Cellular Dynamics Revealed by Digital Holographic Microscopy☆

    KAUST Repository

    Marquet, P.; Depeursinge, Christian; Jourdain, P.

    2016-01-01

    Digital holographic microscopy (DHM) is a new optical method that provides, without the use of any contrast agent, real-time, three-dimensional images of transparent living cells, with an axial sensitivity of a few tens of nanometers. They result from the hologram numerical reconstruction process, which permits a sub wavelength calculation of the phase shift, produced on the transmitted wave front, by the optically probed cells, namely the quantitative phase signal (QPS). Specifically, in addition to measurements of cellular surface morphometry and intracellular refractive index (RI), various biophysical cellular parameters including dry mass, absolute volume, membrane fluctuations at the nanoscale and biomechanical properties, transmembrane water permeability as swell as current, can be derived from the QPS. This article presents how quantitative phase DHM (QP-DHM) can explored cell dynamics at the nanoscale with a special attention to both the study of neuronal dynamics and the optical resolution of local neuronal network.

  3. Tropomodulins and tropomyosins - organizers of cellular microcompartments.

    Science.gov (United States)

    Fath, Thomas

    2013-02-01

    Eukaryotic cells show a remarkable compartmentalization into compartments such as the cell nucleus, the Golgi apparatus, the endoplasmic reticulum, and endosomes. However, organelle structures are not the only means by which specialized compartments are formed. Recent research shows a critical role for diverse actin filament populations in defining functional compartments, here referred to as microcompartments, in a wide range of cells. These microcompartments are involved in regulating fundamental cellular functions including cell motility, plasma membrane organization, and cellular morphogenesis. In this overview, the importance of two multigene families of actin-associated proteins, tropomodulins and tropomyosins, their interactions with each other, and a large number of other proteins will be discussed in the context of generating specialized actin-based microcompartments.

  4. Cellular Dynamics Revealed by Digital Holographic Microscopy☆

    KAUST Repository

    Marquet, P.

    2016-11-22

    Digital holographic microscopy (DHM) is a new optical method that provides, without the use of any contrast agent, real-time, three-dimensional images of transparent living cells, with an axial sensitivity of a few tens of nanometers. They result from the hologram numerical reconstruction process, which permits a sub wavelength calculation of the phase shift, produced on the transmitted wave front, by the optically probed cells, namely the quantitative phase signal (QPS). Specifically, in addition to measurements of cellular surface morphometry and intracellular refractive index (RI), various biophysical cellular parameters including dry mass, absolute volume, membrane fluctuations at the nanoscale and biomechanical properties, transmembrane water permeability as swell as current, can be derived from the QPS. This article presents how quantitative phase DHM (QP-DHM) can explored cell dynamics at the nanoscale with a special attention to both the study of neuronal dynamics and the optical resolution of local neuronal network.

  5. Cellular automata in image processing and geometry

    CERN Document Server

    Adamatzky, Andrew; Sun, Xianfang

    2014-01-01

    The book presents findings, views and ideas on what exact problems of image processing, pattern recognition and generation can be efficiently solved by cellular automata architectures. This volume provides a convenient collection in this area, in which publications are otherwise widely scattered throughout the literature. The topics covered include image compression and resizing; skeletonization, erosion and dilation; convex hull computation, edge detection and segmentation; forgery detection and content based retrieval; and pattern generation. The book advances the theory of image processing, pattern recognition and generation as well as the design of efficient algorithms and hardware for parallel image processing and analysis. It is aimed at computer scientists, software programmers, electronic engineers, mathematicians and physicists, and at everyone who studies or develops cellular automaton algorithms and tools for image processing and analysis, or develops novel architectures and implementations of mass...

  6. Cellular automata and statistical mechanical models

    International Nuclear Information System (INIS)

    Rujan, P.

    1987-01-01

    The authors elaborate on the analogy between the transfer matrix of usual lattice models and the master equation describing the time development of cellular automata. Transient and stationary properties of probabilistic automata are linked to surface and bulk properties, respectively, of restricted statistical mechanical systems. It is demonstrated that methods of statistical physics can be successfully used to describe the dynamic and the stationary behavior of such automata. Some exact results are derived, including duality transformations, exact mappings, disorder, and linear solutions. Many examples are worked out in detail to demonstrate how to use statistical physics in order to construct cellular automata with desired properties. This approach is considered to be a first step toward the design of fully parallel, probabilistic systems whose computational abilities rely on the cooperative behavior of their components

  7. Quantum features of natural cellular automata

    International Nuclear Information System (INIS)

    Elze, Hans-Thomas

    2016-01-01

    Cellular automata can show well known features of quantum mechanics, such as a linear rule according to which they evolve and which resembles a discretized version of the Schrödinger equation. This includes corresponding conservation laws. The class of “natural” Hamiltonian cellular automata is based exclusively on integer-valued variables and couplings and their dynamics derives from an Action Principle. They can be mapped reversibly to continuum models by applying Sampling Theory. Thus, “deformed” quantum mechanical models with a finite discreteness scale l are obtained, which for l → 0 reproduce familiar continuum results. We have recently demonstrated that such automata can form “multipartite” systems consistently with the tensor product structures of nonrelativistic many-body quantum mechanics, while interacting and maintaining the linear evolution. Consequently, the Superposition Principle fully applies for such primitive discrete deterministic automata and their composites and can produce the essential quantum effects of interference and entanglement. (paper)

  8. Minimal entropy approximation for cellular automata

    International Nuclear Information System (INIS)

    Fukś, Henryk

    2014-01-01

    We present a method for the construction of approximate orbits of measures under the action of cellular automata which is complementary to the local structure theory. The local structure theory is based on the idea of Bayesian extension, that is, construction of a probability measure consistent with given block probabilities and maximizing entropy. If instead of maximizing entropy one minimizes it, one can develop another method for the construction of approximate orbits, at the heart of which is the iteration of finite-dimensional maps, called minimal entropy maps. We present numerical evidence that the minimal entropy approximation sometimes outperforms the local structure theory in characterizing the properties of cellular automata. The density response curve for elementary CA rule 26 is used to illustrate this claim. (paper)

  9. Cellular and Molecular Basis of Cerebellar Development

    Directory of Open Access Journals (Sweden)

    Salvador eMartinez

    2013-06-01

    Full Text Available Historically, the molecular and cellular mechanisms of cerebellar development were investigated through structural descriptions and studying spontaneous mutations in animal models and humans. Advances in experimental embryology, genetic engineering and neuroimaging techniques render today the possibility to approach the analysis of molecular mechanisms underlying histogenesis and morphogenesis of the cerebellum by experimental designs. Several genes and molecules were identified to be involved in the cerebellar plate regionalization, specification and differentiation of cerebellar neurons, as well as the establishment of cellular migratory routes and the subsequent neuronal connectivity. Indeed, pattern formation of the cerebellum requires the adequate orchestration of both key morphogenetic signals, arising from distinct brain regions, and local expression of specific transcription factors. Thus, the present review wants to revisit and discuss these morphogenetic and molecular mechanisms taking place during cerebellar development in order to understand causal processes regulating cerebellar cytoarchitecture, its highly topographically ordered circuitry and its role in brain function.

  10. Programmed cellular response to ionizing radiation damage

    International Nuclear Information System (INIS)

    Crompton, N.E.A.

    1998-01-01

    Three forms of radiation response were investigated to evaluate the hypothesis that cellular radiation response is the result of active molecular signaling and not simply a passive physicochemical process. The decision whether or not a cell should respond to radiation-induced damage either by induction of rescue systems, e.g. mobilization of repair proteins, or induction of suicide mechanisms, e.g. programmed cell death, appears to be the expression of intricate cellular biochemistry. A cell must recognize damage in its genetic material and then activate the appropriate responses. Cell type is important; the response of a fibroblast to radiation damage is both quantitatively and qualitatively different form that of a lymphocyte. The programmed component of radiation response is significant in radiation oncology and predicted to create unique opportunities for enhanced treatment success. (orig.)

  11. [Incontinentia pigmenti with defect in cellular immunity].

    Science.gov (United States)

    Zamora-Chávez, Antonio; Escobar-Sánchez, Argelia; Sadowinski-Pine, Stanislaw; Saucedo-Ramírez, Omar Josué; Delgado-Barrera, Palmira; Enríquez-Quiñones, Claudia G

    Incontinentia pigmenti is a rare, X-linked genetic disease and affects all ectoderm-derived tissues such as skin, appendages, eyes, teeth and central nervous system as well as disorders of varying degree of cellular immunity characterized by decreasing melanin in the epidermis and increase in the dermis. When the condition occurs in males, it is lethal. We present the case of a 2-month-old infant with severe incontinentia pigmenti confirmed by histological examination of skin biopsy. The condition evolved with severe neurological disorders and seizures along with severe cellular immune deficiency, which affected the development of severe infections and caused the death of the patient. The importance of early clinical diagnosis is highlighted along with the importance of multidisciplinary management of neurological disorders and infectious complications. Copyright © 2015 Hospital Infantil de México Federico Gómez. Publicado por Masson Doyma México S.A. All rights reserved.

  12. Cellular Mechanisms of Somatic Stem Cell Aging

    Science.gov (United States)

    Jung, Yunjoon

    2014-01-01

    Tissue homeostasis and regenerative capacity rely on rare populations of somatic stem cells endowed with the potential to self-renew and differentiate. During aging, many tissues show a decline in regenerative potential coupled with a loss of stem cell function. Cells including somatic stem cells have evolved a series of checks and balances to sense and repair cellular damage to maximize tissue function. However, during aging the mechanisms that protect normal cell function begin to fail. In this review, we will discuss how common cellular mechanisms that maintain tissue fidelity and organismal lifespan impact somatic stem cell function. We will highlight context-dependent changes and commonalities that define aging, by focusing on three age-sensitive stem cell compartments: blood, neural, and muscle. Understanding the interaction between extrinsic regulators and intrinsic effectors that operate within different stem cell compartments is likely to have important implications for identifying strategies to improve health span and treat age-related degenerative diseases. PMID:24439814

  13. Cellular responses to environmental DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    1994-08-01

    This volume contains the proceedings of the conference entitled Cellular Responses to Environmental DNA Damage held in Banff,Alberta December 1--6, 1991. The conference addresses various aspects of DNA repair in sessions titled DNA repair; Basic Mechanisms; Lesions; Systems; Inducible Responses; Mutagenesis; Human Population Response Heterogeneity; Intragenomic DNA Repair Heterogeneity; DNA Repair Gene Cloning; Aging; Human Genetic Disease; and Carcinogenesis. Individual papers are represented as abstracts of about one page in length.

  14. Towards Massive Machine Type Cellular Communications

    OpenAIRE

    Dawy, Zaher; Saad, Walid; Ghosh, Arunabha; Andrews, Jeffrey G.; Yaacoub, Elias

    2015-01-01

    Cellular networks have been engineered and optimized to carrying ever-increasing amounts of mobile data, but over the last few years, a new class of applications based on machine-centric communications has begun to emerge. Automated devices such as sensors, tracking devices, and meters - often referred to as machine-to-machine (M2M) or machine-type communications (MTC) - introduce an attractive revenue stream for mobile network operators, if a massive number of them can be efficiently support...

  15. Cognitive resource management for heterogeneous cellular networks

    CERN Document Server

    Liu, Yongkang

    2014-01-01

    This Springer Brief focuses on cognitive resource management in heterogeneous cellular networks (Het Net) with small cell deployment for the LTE-Advanced system. It introduces the Het Net features, presents practical approaches using cognitive radio technology in accommodating small cell data relay and optimizing resource allocation and examines the effectiveness of resource management among small cells given limited coordination bandwidth and wireless channel uncertainty. The authors introduce different network characteristics of small cell, investigate the mesh of small cell access points in

  16. Cellular radiobiology of heavy-ion beams

    International Nuclear Information System (INIS)

    Tobias, C.A.; Blakely, E.A.; Ngo, F.Q.H.; Roots, R.J.; Yang, T.C.

    1981-01-01

    Progress is reported in the following areas of this research program: relative biological effectiveness and oxygen enhancement ratio of silicon ion beams; heavy ion effects on the cell cycle; the potentiation effect (2 doses of high LET heavy-ion radiations separated by 2 to 3 hours); potentially lethal damage in actively growing cells and plateau growth cells; radiation induced macromolecular lesions and cellular radiation chemistry; lethal effects of dual radiation; and the development of a biophysical repair/misrepair model

  17. Cellular-based sea level gauge

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, R.G.P.; Joseph, A.

    treaties with greater transparency. Among the various communication technologies used for real-time transmission of sea-level data are the wired telephone connection, VHF/UHF transceivers, satellite transmit terminals and cellular connectivity. Wired... telephone connections are severely susceptible to loss of connectivity during natural disasters such as storm surges, primarily because of telephone line breakage. Communication via VHF/UHF transceivers is limited by line-of-sight distance between...

  18. Cellular automata in photonic cavity arrays.

    Science.gov (United States)

    Li, Jing; Liew, T C H

    2016-10-31

    We propose theoretically a photonic Turing machine based on cellular automata in arrays of nonlinear cavities coupled with artificial gauge fields. The state of the system is recorded making use of the bistability of driven cavities, in which losses are fully compensated by an external continuous drive. The sequential update of the automaton layers is achieved automatically, by the local switching of bistable states, without requiring any additional synchronization or temporal control.

  19. How to detect integrability in cellular automata

    International Nuclear Information System (INIS)

    Joshi, N; Lafortune, S

    2005-01-01

    Ultra-discrete equations are generalized cellular automata in the sense that the dependent (and independent) variables take only integer values. We present a new method for identifying integrable ultra-discrete equations which is the equivalent of the singularity confinement property for difference equations and the Painleve property for differential equations. Using this criterion, we find integrable ultra-discrete equations which include the ultra-discrete Painleve equations. (letter to the editor)

  20. Cellular mechanisms of nociception in the frog

    Czech Academy of Sciences Publication Activity Database

    Kuffler, D. P.; Lyfenko, Alla; Vyklický st., Ladislav; Vlachová, Viktorie

    2002-01-01

    Roč. 88, č. 4 (2002), s. 1843-1850 ISSN 0022-3077 R&D Projects: GA ČR GA305/00/1639; GA MŠk LN00B122 Grant - others:NATO(XX) Grant 977062 Institutional research plan: CEZ:AV0Z5011922 Keywords : cellular mechanisms of nociception * frog Subject RIV: FH - Neurology Impact factor: 3.743, year: 2002

  1. Cellular and Chemical Neuroscience of Mammalian Sleep

    OpenAIRE

    Datta, Subimal

    2010-01-01

    Extraordinary strides have been made toward understanding the complexities and regulatory mechanisms of sleep over the past two decades, thanks to the help of rapidly evolving technologies. At its most basic level, mammalian sleep is a restorative process of the brain and body. Beyond its primary restorative purpose, sleep is essential for a number of vital functions. Our primary research interest is to understand the cellular and molecular mechanisms underlying the regulation of sleep and it...

  2. Image processing with a cellular nonlinear network

    International Nuclear Information System (INIS)

    Morfu, S.

    2005-01-01

    A cellular nonlinear network (CNN) based on uncoupled nonlinear oscillators is proposed for image processing purposes. It is shown theoretically and numerically that the contrast of an image loaded at the nodes of the CNN is strongly enhanced, even if this one is initially weak. An image inversion can be also obtained without reconfiguration of the network whereas a gray levels extraction can be performed with an additional threshold filtering. Lastly, an electronic implementation of this CNN is presented

  3. Additive Cellular Automata and Volume Growth

    Directory of Open Access Journals (Sweden)

    Thomas B. Ward

    2000-08-01

    Full Text Available Abstract: A class of dynamical systems associated to rings of S-integers in rational function fields is described. General results about these systems give a rather complete description of the well-known dynamics in one-dimensional additive cellular automata with prime alphabet, including simple formulæ for the topological entropy and the number of periodic configurations. For these systems the periodic points are uniformly distributed along some subsequence with respect to the maximal measure, and in particular are dense. Periodic points may be constructed arbitrarily close to a given configuration, and rationality of the dynamical zeta function is characterized. Throughout the emphasis is to place this particular family of cellular automata into the wider context of S-integer dynamical systems, and to show how the arithmetic of rational function fields determines their behaviour. Using a covering space the dynamics of additive cellular automata are related to a form of hyperbolicity in completions of rational function fields. This expresses the topological entropy of the automata directly in terms of volume growth in the covering space.

  4. Cellular signaling identifiability analysis: a case study.

    Science.gov (United States)

    Roper, Ryan T; Pia Saccomani, Maria; Vicini, Paolo

    2010-05-21

    Two primary purposes for mathematical modeling in cell biology are (1) simulation for making predictions of experimental outcomes and (2) parameter estimation for drawing inferences from experimental data about unobserved aspects of biological systems. While the former purpose has become common in the biological sciences, the latter is less common, particularly when studying cellular and subcellular phenomena such as signaling-the focus of the current study. Data are difficult to obtain at this level. Therefore, even models of only modest complexity can contain parameters for which the available data are insufficient for estimation. In the present study, we use a set of published cellular signaling models to address issues related to global parameter identifiability. That is, we address the following question: assuming known time courses for some model variables, which parameters is it theoretically impossible to estimate, even with continuous, noise-free data? Following an introduction to this problem and its relevance, we perform a full identifiability analysis on a set of cellular signaling models using DAISY (Differential Algebra for the Identifiability of SYstems). We use our analysis to bring to light important issues related to parameter identifiability in ordinary differential equation (ODE) models. We contend that this is, as of yet, an under-appreciated issue in biological modeling and, more particularly, cell biology. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  5. Thermal expansion behavior in fabricated cellular structures

    International Nuclear Information System (INIS)

    Oruganti, R.K.; Ghosh, A.K.; Mazumder, J.

    2004-01-01

    Thermal expansion behavior of cellular structures is of interest in applications where undesirable deformation and failure are caused by thermal expansion mismatch. This report describes the role of processing-induced effects and metallurgical aspects of melt-processed cellular structures, such as a bi-material structure designed to contract on heating, as well as uni-material structures of regular and stochastic topology. This bi-material structure utilized the principle of internal geometric constraints to alter the expansion behavior of the internal ligaments to create overall contraction of the structure. Homogenization design method was used to design the structure, and fabrication was by direct metal deposition by laser melting of powder in another part of a joint effort. The degree of porosity and grain size in the fabricated structure are characterized and related to the laser deposition parameters. The structure was found to contract upon heating over a short range of temperature subsequent to which normal expansion ensued. Also examined in this report are uni-material cellular structures, in which internal constraints arise from residual stress variations caused by the fabrication process, and thereby alter their expansion characteristics. A simple analysis of thermal strain of this material supports the observed thermal expansion behavior

  6. Literature Review on Dynamic Cellular Manufacturing System

    Science.gov (United States)

    Nouri Houshyar, A.; Leman, Z.; Pakzad Moghadam, H.; Ariffin, M. K. A. M.; Ismail, N.; Iranmanesh, H.

    2014-06-01

    In previous decades, manufacturers faced a lot of challenges because of globalization and high competition in markets. These problems arise from shortening product life cycle, rapid variation in demand of products, and also rapid changes in manufcaturing technologies. Nowadays most manufacturing companies expend considerable attention for improving flexibility and responsiveness in order to overcome these kinds of problems and also meet customer's needs. By considering the trend toward the shorter product life cycle, the manufacturing environment is towards manufacturing a wide variety of parts in small batches [1]. One of the major techniques which are applied for improving manufacturing competitiveness is Cellular Manufacturing System (CMS). CMS is type of manufacturing system which tries to combine flexibility of job shop and also productivity of flow shop. In addition, Dynamic cellular manufacturing system which considers different time periods for the manufacturing system becomes an important topic and attracts a lot of attention to itself. Therefore, this paper made attempt to have a brief review on this issue and focused on all published paper on this subject. Although, this topic gains a lot of attention to itself during these years, none of previous researchers focused on reviewing the literature of that which can be helpful and useful for other researchers who intend to do the research on this topic. Therefore, this paper is the first study which has focused and reviewed the literature of dynamic cellular manufacturing system.

  7. Inter-cellular transport of ran GTPase.

    Directory of Open Access Journals (Sweden)

    Deepak Khuperkar

    Full Text Available Ran, a member of the Ras-GTPase superfamily, has a well-established role in regulating the transport of macromolecules across the nuclear envelope (NE. Ran has also been implicated in mitosis, cell cycle progression, and NE formation. Over-expression of Ran is associated with various cancers, although the molecular mechanism underlying this phenomenon is unclear. Serendipitously, we found that Ran possesses the ability to move from cell-to-cell when transiently expressed in mammalian cells. Moreover, we show that the inter-cellular transport of Ran is GTP-dependent. Importantly, Ran displays a similar distribution pattern in the recipient cells as that in the donor cell and co-localizes with the Ran binding protein Nup358 (also called RanBP2. Interestingly, leptomycin B, an inhibitor of CRM1-mediated export, or siRNA mediated depletion of CRM1, significantly impaired the inter-cellular transport of Ran, suggesting a function for CRM1 in this process. These novel findings indicate a possible role for Ran beyond nucleo-cytoplasmic transport, with potential implications in inter-cellular communication and cancers.

  8. HDACi: cellular effects, opportunities for restorative dentistry.

    LENUS (Irish Health Repository)

    Duncan, H F

    2011-12-01

    Acetylation of histone and non-histone proteins alters gene expression and induces a host of cellular effects. The acetylation process is homeostatically balanced by two groups of cellular enzymes, histone acetyltransferases (HATs) and histone deacetylases (HDACs). HAT activity relaxes the structure of the human chromatin, rendering it transcriptionally active, thereby increasing gene expression. In contrast, HDAC activity leads to gene silencing. The enzymatic balance can be \\'tipped\\' by histone deacetylase inhibitors (HDACi), leading to an accumulation of acetylated proteins, which subsequently modify cellular processes including stem cell differentiation, cell cycle, apoptosis, gene expression, and angiogenesis. There is a variety of natural and synthetic HDACi available, and their pleiotropic effects have contributed to diverse clinical applications, not only in cancer but also in non-cancer areas, such as chronic inflammatory disease, bone engineering, and neurodegenerative disease. Indeed, it appears that HDACi-modulated effects may differ between \\'normal\\' and transformed cells, particularly with regard to reactive oxygen species accumulation, apoptosis, proliferation, and cell cycle arrest. The potential beneficial effects of HDACi for health, resulting from their ability to regulate global gene expression by epigenetic modification of DNA-associated proteins, also offer potential for application within restorative dentistry, where they may promote dental tissue regeneration following pulpal damage.

  9. Cellular Kinetics of Perivascular MSC Precursors

    Directory of Open Access Journals (Sweden)

    William C. W. Chen

    2013-01-01

    Full Text Available Mesenchymal stem/stromal cells (MSCs and MSC-like multipotent stem/progenitor cells have been widely investigated for regenerative medicine and deemed promising in clinical applications. In order to further improve MSC-based stem cell therapeutics, it is important to understand the cellular kinetics and functional roles of MSCs in the dynamic regenerative processes. However, due to the heterogeneous nature of typical MSC cultures, their native identity and anatomical localization in the body have remained unclear, making it difficult to decipher the existence of distinct cell subsets within the MSC entity. Recent studies have shown that several blood-vessel-derived precursor cell populations, purified by flow cytometry from multiple human organs, give rise to bona fide MSCs, suggesting that the vasculature serves as a systemic reservoir of MSC-like stem/progenitor cells. Using individually purified MSC-like precursor cell subsets, we and other researchers have been able to investigate the differential phenotypes and regenerative capacities of these contributing cellular constituents in the MSC pool. In this review, we will discuss the identification and characterization of perivascular MSC precursors, including pericytes and adventitial cells, and focus on their cellular kinetics: cell adhesion, migration, engraftment, homing, and intercellular cross-talk during tissue repair and regeneration.

  10. Image Encryption and Chaotic Cellular Neural Network

    Science.gov (United States)

    Peng, Jun; Zhang, Du

    Machine learning has been playing an increasingly important role in information security and assurance. One of the areas of new applications is to design cryptographic systems by using chaotic neural network due to the fact that chaotic systems have several appealing features for information security applications. In this chapter, we describe a novel image encryption algorithm that is based on a chaotic cellular neural network. We start by giving an introduction to the concept of image encryption and its main technologies, and an overview of the chaotic cellular neural network. We then discuss the proposed image encryption algorithm in details, which is followed by a number of security analyses (key space analysis, sensitivity analysis, information entropy analysis and statistical analysis). The comparison with the most recently reported chaos-based image encryption algorithms indicates that the algorithm proposed in this chapter has a better security performance. Finally, we conclude the chapter with possible future work and application prospects of the chaotic cellular neural network in other information assurance and security areas.

  11. Cellularity of certain quantum endomorphism algebras

    DEFF Research Database (Denmark)

    Andersen, Henning Haahr; Lehrer, Gus; Zhang, Ruibin

    2015-01-01

    For any ring A˜ such that Z[q±1∕2]⊆A˜⊆Q(q1∕2), let ΔA˜(d) be an A˜-form of the Weyl module of highest weight d∈N of the quantised enveloping algebra UA˜ of sl2. For suitable A˜, we exhibit for all positive integers r an explicit cellular structure for EndUA˜(ΔA˜(d)⊗r). This algebra and its cellular...... structure are described in terms of certain Temperley–Lieb-like diagrams. We also prove general results that relate endomorphism algebras of specialisations to specialisations of the endomorphism algebras. When ζ is a root of unity of order bigger than d we consider the Uζ-module structure...... of the specialisation Δζ(d)⊗r at q↦ζ of ΔA˜(d)⊗r. As an application of these results, we prove that knowledge of the dimensions of the simple modules of the specialised cellular algebra above is equivalent to knowledge of the weight multiplicities of the tilting modules for Uζ(sl2). As an example, in the final section...

  12. Cellular vs. organ approaches to dose estimates

    International Nuclear Information System (INIS)

    Adelstein, S.J.; Kassis, A.I.; Sastry, K.S.R.

    1986-01-01

    The cellular distribution of tissue-incorporated radionuclides has generally been neglected in the dosimetry of internal emitters. Traditional dosimetry assumes homogeneous distribution of radionuclides in organs of interest, while presuming that the ranges of particulate radiations are large relative to typical cell diameters. The macroscopic distribution of dose thus calculated has generally served as a sufficient approximation for the energy deposited within radiosensitive sites. However, with the increasing utilization of intracellular agents, such as thallium-201, it has become necessary to examine the microscopic distribution of energy at the cellular level. This is particularly important in the instance of radionuclides that decay by electron capture or by internal conversion with the release of Auger and Coster-Kronig electrons. In many instances, these electrons are released as a dense shower of low-energy particles with ranges of subcellular dimensions. The high electron density in the immediate vicinity of the decaying atom produces a focal deposition of energy that far exceeds the average dose taken over several cell diameters. These studies point out the increasing need to take into account the microscopic distribution of dose on the cellular level as radionuclides distributed in cells become more commonplace, especially if the decay involves electron capture or internal conversion. As radiotracers are developed for the measurement of intracellular functions these factors should be given greater consideration. 16 references, 5 figures, 5 tables

  13. Recursive definition of global cellular-automata mappings

    International Nuclear Information System (INIS)

    Feldberg, R.; Knudsen, C.; Rasmussen, S.

    1994-01-01

    A method for a recursive definition of global cellular-automata mappings is presented. The method is based on a graphical representation of global cellular-automata mappings. For a given cellular-automaton rule the recursive algorithm defines the change of the global cellular-automaton mapping as the number of lattice sites is incremented. A proof of lattice size invariance of global cellular-automata mappings is derived from an approximation to the exact recursive definition. The recursive definitions are applied to calculate the fractal dimension of the set of reachable states and of the set of fixed points of cellular automata on an infinite lattice

  14. Chunk-Based Energy Efficient Resource Allocation in OFDMA Systems

    Directory of Open Access Journals (Sweden)

    Yong Li

    2013-01-01

    Full Text Available Energy efficiency (EE capacity analysis of the chunk-based resource allocation is presented by considering the minimum spectrum efficiency (SE constraint in downlink multiuser orthogonal frequency division multiplexing (OFDM systems. Considering the minimum SE requirement, an optimization problem to maximize EE with limited transmit power is formulated over frequency selective channels. Based on this model, a low-complexity energy efficient resource allocation is proposed. The effects of system parameters, such as the average channel gain-to-noise ratio (CNR and the number of subcarriers per chunk, are evaluated. Numerical results demonstrate the effectiveness of the proposed scheme for balancing the EE and SE.

  15. Location-Based Resource Allocation for OFDMA Cognitive Radio Systems

    KAUST Repository

    Ghorbel, Mahdi

    2011-05-01

    Cognitive radio is one of the hot topics for emerging and future wireless communication. It has been proposed as a suitable solution for the spectrum scarcity caused by the increase in frequency demand. The concept is based on allowing unlicensed users, called cognitive or secondary users, to share the unoccupied frequency bands with their owners, called the primary users, under constraints on the interference they cause to them. In order to estimate this interference, the cognitive system usually uses the channel state information to the primary user, which is often impractical to obtain. However, we propose to use location information, which is easier to obtain, to estimate this interference. The purpose of this work is to propose a subchannel and power allocation method which maximizes the secondary users\\' total capacity under the constraints of limited budget power and total interference to the primary under certain threshold. We model the problem as a constrained optimization problem for both downlink and uplink cases. Then, we propose low-complexity resource allocation schemes based on the waterfilling algorithm. The simulation results show the efficiency of the proposed method with comparison to the exhaustive search algorithm.

  16. Adaptive Modulation for a Downlink Multicast Channel in OFDMA Systems

    DEFF Research Database (Denmark)

    Wang, Haibo; Schwefel, Hans-Peter; Toftegaard, Thomas Skjødeberg

    2007-01-01

    In this paper we focus on adaptive modulation strategies for multicast service in orthogonal frequency division multiple access systems. A reward function has been defined as the optimization target, which includes both the average user throughput and bit error rate. We also developed an adaptive...... modulation strategy, namely local best reward strategy, to maximize this reward function. The performance of different modulation strategies are compared in different SNR distribution scenarios, and the optimum strategy in each scenario is suggested....

  17. Location-based resource allocation for OFDMA cognitive radio systems

    KAUST Repository

    Nam, Haewoon; Ben Ghorbel, Mahdi; Alouini, Mohamed-Slim

    2010-01-01

    In cognitive radio systems, in order for the secondary users to opportunistically share the spectrum without interfering the primary users, an accurate spectrum measurement and a precise estimation of the interference at the primary users

  18. Weighted-SNR-based fair scheduling for uplink OFDMA

    KAUST Repository

    Ma, Yao; Leith, Alex; Alouini, Mohamed-Slim; (Sherman) Shen X., Xuemin

    2009-01-01

    rates for different users. The offline optimization technique requires to know the channel distribution information (CDI) at the scheduler. The online method uses the weight adaption combined with individual user rate tracking, which avoids the need

  19. Secure physical layer using dynamic permutations in cognitive OFDMA systems

    DEFF Research Database (Denmark)

    Meucci, F.; Wardana, Satya Ardhy; Prasad, Neeli R.

    2009-01-01

    This paper proposes a novel lightweight mechanism for a secure Physical (PHY) layer in Cognitive Radio Network (CRN) using Orthogonal Frequency Division Multiplexing (OFDM). User's data symbols are mapped over the physical subcarriers with a permutation formula. The PHY layer is secured...... with a random and dynamic subcarrier permutation which is based on a single pre-shared information and depends on Dynamic Spectrum Access (DSA). The dynamic subcarrier permutation is varying over time, geographical location and environment status, resulting in a very robust protection that ensures...... confidentiality. The method is shown to be effective also for existing non-cognitive systems. The proposed mechanism is effective against eavesdropping even if the eavesdropper adopts a long-time patterns analysis, thus protecting cryptography techniques of higher layers. The correlation properties...

  20. Cellular membrane trafficking of mesoporous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Fang, I-Ju [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  1. Dynamic spectrum management in green cognitive radio cellular networks

    KAUST Repository

    Sboui, Lokman; Ghazzai, Hakim; Rezki, Zouheir; Alouini, Mohamed-Slim

    2018-01-01

    In this paper, we propose a new cellular network operation scheme fulfilling the 5G requirements related to spectrum management and green communications. We focus on cognitive radio cellular networks in which both the primary network (PN

  2. Shape Memory Alloy-Based Periodic Cellular Structures, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase II effort will continue to develop and demonstrate an innovative shape memory alloy (SMA) periodic cellular structural technology. Periodic cellular...

  3. Computational Complexity of Some Problems on Generalized Cellular Automations

    Directory of Open Access Journals (Sweden)

    P. G. Klyucharev

    2012-03-01

    Full Text Available We prove that the preimage problem of a generalized cellular automation is NP-hard. The results of this work are important for supporting the security of the ciphers based on the cellular automations.

  4. Error performance analysis in downlink cellular networks with interference management

    KAUST Repository

    Afify, Laila H.; Elsawy, Hesham; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    Modeling aggregate network interference in cellular networks has recently gained immense attention both in academia and industry. While stochastic geometry based models have succeeded to account for the cellular network geometry, they mostly

  5. A generalized cellular automata approach to modeling first order ...

    Indian Academy of Sciences (India)

    system, consisting of space, time and state, structured with simple local rules without ... Sensitivity analysis of a stochastic cellular automata model. 413 ..... Baetens J M and De Baets B 2011 Design and parameterization of a stochastic cellular.

  6. Cellular Particle Dynamics simulation of biomechanical relaxation processes of multi-cellular systems

    Science.gov (United States)

    McCune, Matthew; Kosztin, Ioan

    2013-03-01

    Cellular Particle Dynamics (CPD) is a theoretical-computational-experimental framework for describing and predicting the time evolution of biomechanical relaxation processes of multi-cellular systems, such as fusion, sorting and compression. In CPD, cells are modeled as an ensemble of cellular particles (CPs) that interact via short range contact interactions, characterized by an attractive (adhesive interaction) and a repulsive (excluded volume interaction) component. The time evolution of the spatial conformation of the multicellular system is determined by following the trajectories of all CPs through numerical integration of their equations of motion. Here we present CPD simulation results for the fusion of both spherical and cylindrical multi-cellular aggregates. First, we calibrate the relevant CPD model parameters for a given cell type by comparing the CPD simulation results for the fusion of two spherical aggregates to the corresponding experimental results. Next, CPD simulations are used to predict the time evolution of the fusion of cylindrical aggregates. The latter is relevant for the formation of tubular multi-cellular structures (i.e., primitive blood vessels) created by the novel bioprinting technology. Work supported by NSF [PHY-0957914]. Computer time provided by the University of Missouri Bioinformatics Consortium.

  7. Integrated Transceivers for Millimeter Wave and Cellular Communication

    OpenAIRE

    TIRED, TOBIAS

    2016-01-01

    Abstract:This doctoral thesis is addresses two topics in integrated circuit design: multiband direct conversion cellular receivers for cellular frequencies and beam steering transmitters for millimeter wave communication for the cellular backhaul. The trend towards cellular terminals supporting ever more different frequency bands has resulted in complex radio frontends with a large number of RF inputs. Common receivers have, for performance reasons, in the past used differential RF inputs. Ho...

  8. THE EFFECT OF CELLULAR PHONE USE ON DRIVING PERFORMANCE

    OpenAIRE

    Toshiro ISHIDA

    2001-01-01

    Many experiments using driving simulators or real roads have shown that using a cellular phone while driving may cause an accident because it delays visual information processing by the driver. In this research, we examined the influence on driving performance of cellular phone use on a course that simulated streets. Driving conditions were driving only, listening to the car radio, hands-free cellular phone use and using a cellular phone with the left hand. Driving performance measurements in...

  9. Probing cellular behaviors through nanopatterned chitosan membranes

    International Nuclear Information System (INIS)

    Yang, Chung-Yao; Sung, Chun-Yen; Shuai, Hung-Hsun; Cheng, Chao-Min; Yeh, J Andrew

    2013-01-01

    This paper describes a high-throughput method for developing physically modified chitosan membranes to probe the cellular behavior of MDCK epithelial cells and HIG-82 fibroblasts adhered onto these modified membranes. To prepare chitosan membranes with micro/nanoscaled features, we have demonstrated an easy-to-handle, facile approach that could be easily integrated with IC-based manufacturing processes with mass production potential. These physically modified chitosan membranes were observed by scanning electron microscopy to gain a better understanding of chitosan membrane surface morphology. After MDCK cells and HIG-82 fibroblasts were cultured on these modified chitosan membranes for various culture durations (i.e. 1, 2, 4, 12 and 24 h), they were investigated to decipher cellular behavior. We found that both cells preferred to adhere onto a flat surface rather than on a nanopatterned surface. However, most (> 80%) of the MDCK cells showed rounded morphology and would suspend in the cultured medium instead of adhering onto the planar surface of negatively nanopatterned chitosan membranes. This means different cell types (e.g. fibroblasts versus epithelia) showed distinct capabilities/preferences of adherence for materials of varying surface roughness. We also showed that chitosan membranes could be re-used at least nine times without significant contamination and would provide us consistency for probing cell–material interactions by permitting reuse of the same substrate. We believe these results would provide us better insight into cellular behavior, specifically, microscopic properties and characteristics of cells grown under unique, nanopatterned cell-interface conditions. (paper)

  10. Molecular and cellular mechanisms of cadmium carcinogenesis

    International Nuclear Information System (INIS)

    Waisberg, Michael; Joseph, Pius; Hale, Beverley; Beyersmann, Detmar

    2003-01-01

    Cadmium is a heavy metal, which is widely used in industry, affecting human health through occupational and environmental exposure. In mammals, it exerts multiple toxic effects and has been classified as a human carcinogen by the International Agency for Research on Cancer. Cadmium affects cell proliferation, differentiation, apoptosis and other cellular activities. Cd 2+ does not catalyze Fenton-type reactions because it does not accept or donate electrons under physiological conditions, and it is only weakly genotoxic. Hence, indirect mechanisms are implicated in the carcinogenicity of cadmium. In this review multiple mechanisms are discussed, such as modulation of gene expression and signal transduction, interference with enzymes of the cellular antioxidant system and generation of reactive oxygen species (ROS), inhibition of DNA repair and DNA methylation, role in apoptosis and disruption of E-cadherin-mediated cell-cell adhesion. Cadmium affects both gene transcription and translation. The major mechanisms of gene induction by cadmium known so far are modulation of cellular signal transduction pathways by enhancement of protein phosphorylation and activation of transcription and translation factors. Cadmium interferes with antioxidant defense mechanisms and stimulates the production of reactive oxygen species, which may act as signaling molecules in the induction of gene expression and apoptosis. The inhibition of DNA repair processes by cadmium represents a mechanism by which cadmium enhances the genotoxicity of other agents and may contribute to the tumor initiation by this metal. The disruption of E-cadherin-mediated cell-cell adhesion by cadmium probably further stimulates the development of tumors. It becomes clear that there exist multiple mechanisms which contribute to the carcinogenicity of cadmium, although the relative weights of these contributions are difficult to estimate

  11. Surface Dynamic Process Simulation with the Use of Cellular Automata

    International Nuclear Information System (INIS)

    Adamska-Szatko, M.; Bala, J.

    2010-01-01

    Cellular automata are known for many applications, especially for physical and biological simulations. Universal cellular automata can be used for modelling complex natural phenomena. The paper presents simulation of surface dynamic process. Simulation uses 2-dimensional cellular automata algorithm. Modelling and visualisation were created by in-house developed software with standard OpenGL graphic library. (authors)

  12. 47 CFR 32.5003 - Cellular mobile revenue.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cellular mobile revenue. 32.5003 Section 32... SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Instructions For Revenue Accounts § 32.5003 Cellular mobile revenue. This account shall include message revenue derived from cellular mobile...

  13. Traffic Engineering of Cellular Wireless Communication Systems

    DEFF Research Database (Denmark)

    Iversen, Villy Bæk

    2002-01-01

    In mobile communications an efficient utilisation of the channels is of great importance. In this paper we describe the basic principles for obtaining the maximum utilisation and study strategies for obtaining these limits. In general a high degree of sharing is efficient, but requires service...... protection mechanisms to guarantee the Quality of Service for all services. We study cellular systems with hierarchical cells, and the effect of overlapping cells, and we show that by call packing we obtain a very high utilisation. The models are generalisations of the Erlang-B formula, and include general...

  14. Microwave components for cellular portable radiotelephone

    Science.gov (United States)

    Muraguchi, Masahiro; Aikawa, Masayoshi

    1995-09-01

    Mobile and personal communication systems are expected to represent a huge market for microwave components in the coming years. A number of components in silicon bipolar, silicon Bi-CMOS, GaAs MESFET, HBT and HEMT are now becoming available for system application. There are tradeoffs among the competing technologies with regard to performance, cost, reliability and time-to-market. This paper describes process selection and requirements of cost and r.f. performances to microwave semiconductor components for digital cellular and cordless telephones. Furthermore, new circuit techniques which were developed by NTT are presented.

  15. Biomolecular condensates: organizers of cellular biochemistry.

    Science.gov (United States)

    Banani, Salman F; Lee, Hyun O; Hyman, Anthony A; Rosen, Michael K

    2017-05-01

    Biomolecular condensates are micron-scale compartments in eukaryotic cells that lack surrounding membranes but function to concentrate proteins and nucleic acids. These condensates are involved in diverse processes, including RNA metabolism, ribosome biogenesis, the DNA damage response and signal transduction. Recent studies have shown that liquid-liquid phase separation driven by multivalent macromolecular interactions is an important organizing principle for biomolecular condensates. With this physical framework, it is now possible to explain how the assembly, composition, physical properties and biochemical and cellular functions of these important structures are regulated.

  16. Immunotherapy in allergy and cellular tests

    Science.gov (United States)

    Chirumbolo, Salvatore

    2014-01-01

    The basophil activation test (BAT) is an in vitro assay where the activation of basophils upon exposure to various IgE-challenging molecules is measured by flow cytometry. It is a cellular test able to investigate basophil behavior during allergy and allergy immunotherapy. A panoply of critical issues and suggestive advances have rendered this assay a promising yet puzzling tool to endeavor a full comprehension of innate immunity of allergy desensitization and manage allergen or monoclonal anti-IgE therapy. In this review a brief state of art of BAT in immunotherapy is described focusing onto the analytical issue pertaining BAT performance in allergy specific therapy. PMID:24717453

  17. Intractable problems in reversible cellular automata

    International Nuclear Information System (INIS)

    Vatan, F.

    1988-01-01

    The billiard ball model, a classical mechanical system in which all parameters are real variables, can perform all digital computations. An eight-state, 11-neighbor reversible cellular automaton (an entirely discrete system in which all parameters are integer variables) can simulate this model. One of the natural problems for this system is to determine the shape of a container so that they initial specific distribution of gas molecules eventually leads to a predetermined distribution. This problem if PSPACE-complete. Related intractable and decidable problems are discussed as well

  18. Temporal organization of cellular self-replication

    Science.gov (United States)

    Alexandrov, Victor; Pugatch, Rami

    Recent experiments demonstrate that single cells grow exponentially in time. A coarse grained model of cellular self-replication is presented based on a novel concept - the cell is viewed as a self-replicating queue. This allows to have a more fundamental look into various temporal organizations and, importantly, the inherent non-Markovianity of noise distributions. As an example, the distribution of doubling times can be inferred and compared to single cell experiments in bacteria. We observe data collapse upon scaling by the average doubling time for different environments and present an inherent task allocation trade-off. Support from the Simons Center for Systems Biology, IAS, Princeon.

  19. The oxygen effect and cellular adaptation

    International Nuclear Information System (INIS)

    Meshcherikova, V.V.; Vajnson, A.A.; Yarmonenko, S.P.

    1979-01-01

    The radiomodifying effect of oxygen was shown to depend on the level of cellular oxygenation prior to irradiation. Acute hypoxia created at the time of irradiation protects previously normally oxygenated cells with DMF approximately 1.4 times larger than that of cells cultured for 24 hours under conditions of mild hypoxia. It is suggested that a decrease in the radioprotective effect of acute hypoxia on chronically hypoxic cells is correlated with an appreciable decrease in the rate of oxygen consumption by these cells, due to which the oxygen concentration near the intracellular targets in chronically hypoxic cells may be higher than in normal cells under conditions of poor oxygenation

  20. [Fanconi anemia: cellular and molecular features].

    Science.gov (United States)

    Macé, G; Briot, D; Guervilly, J-H; Rosselli, F

    2007-02-01

    Fanconi anemia (FA) is a recessive human cancer prone syndrome featuring bone marrow failure, developmental abnormalities and hypersensitivity to DNA crosslinking agents exposure. 11 among 12 FA gene have been isolated. The biochemical functions of the FANC proteins remain poorly understood. Anyhow, to cope with DNA crosslinks a cell needs a functional FANC pathway. Moreover, the FANC proteins appear to be involved in cell protection against oxidative damage and in the control of TNF-alpha activity. In this review, we describe the current understanding of the FANC pathway and we present how it may be integrated in the complex networks of proteins involved in maintaining the cellular homeostasis.

  1. Soliton cellular automata associated with crystal bases

    International Nuclear Information System (INIS)

    Hatayama, Goro; Kuniba, Atsuo; Takagi, Taichiro

    2000-01-01

    We introduce a class of cellular automata associated with crystals of irreducible finite dimensional representations of quantum affine algebras U' q (g-circumflex n ). They have solitons labeled by crystals of the smaller algebra U' q (g-circumflex n-1 ). We prove stable propagation of one soliton for g-circumflex n =A (2) 2n-1 ,A (2) 2n ,B (1) n ,C (1) n ,D (1) n and D (2) n+1 . For g-circumflex n =C (1) n , we also prove that the scattering matrices of two solitons coincide with the combinatorial R matrices of U' q (C (1) n-1 )-crystals

  2. Cellular mechanisms within the juxtaglomerular apparatus

    DEFF Research Database (Denmark)

    Briggs, J P; Skøtt, O; Schnermann, J

    1990-01-01

    Cl concentration at the macular densa. This change also results in inhibition of secretion of renin. The macula densa has a unique location near the terminal end of the thick ascending limb, where NaCl concentration is highly flow dependent. The cellular mechanisms by which changes in tubular fluid NaCl produce...... vasoconstriction and inhibition of renin secretion are unknown, but the anatomy of the juxtaglomerular apparatus strongly suggests that such responses may be mediated by the extraglomerular mesangial cells located in the polar cushion underlying the macula densa. Recent evidence suggests that interstitial chloride...

  3. Conference on radionuclide labelled cellular blood elements

    International Nuclear Information System (INIS)

    1986-01-01

    The South African Medical Research Council presented this conference on radionuclide labelled cellular blood elements with application in atherosclerosis and thrombosis. The conference was held in Bloemfontein from 3-6 February 1986. This work only consists of the abstracts of the seminars that were delivered on the conference. The radioisotopes that occur most of the time in the abstracts include Indium 111, Indium 114, Chromium 51, Iodine 125, Iodine 131 and Carbon 14. Especially Indium 111 seems to be the method of choice for all labelling

  4. Dynamic behavior of cellular materials and cellular structures: Experiments and modeling

    Science.gov (United States)

    Gao, Ziyang

    Cellular solids, including cellular materials and cellular structures (CMS), have attracted people's great interests because of their low densities and novel physical, mechanical, thermal, electrical and acoustic properties. They offer potential for lightweight structures, energy absorption, thermal management, etc. Therefore, the studies of cellular solids have become one of the hottest research fields nowadays. From energy absorption point of view, any plastically deformed structures can be divided into two types (called type I and type II), and the basic cells of the CMS may take the configurations of these two types of structures. Accordingly, separated discussions are presented in this thesis. First, a modified 1-D model is proposed and numerically solved for a typical type II structure. Good agreement is achieved with the previous experimental data, hence is used to simulate the dynamic behavior of a type II chain. Resulted from different load speeds, interesting collapse modes are observed, and the parameters which govern the cell's post-collapse behavior are identified through a comprehensive non-dimensional analysis on general cellular chains. Secondly, the MHS specimens are chosen as an example of type I foam materials because of their good uniformity of the cell geometry. An extensive experimental study was carried out, where more attention was paid to their responses to dynamic loadings. Great enhancement of the stress-strain curve was observed in dynamic cases, and the energy absorption capacity is found to be several times higher than that of the commercial metal foams. Based on the experimental study, finite elemental simulations and theoretical modeling are also conducted, achieving good agreements and demonstrating the validities of those models. It is believed that the experimental, numerical and analytical results obtained in the present study will certainly deepen the understanding of the unsolved fundamental issues on the mechanical behavior of

  5. Mechanisms and cellular functions of intramembrane proteases.

    Science.gov (United States)

    Urban, Siniša

    2013-12-01

    The turn of the millennium coincided with the branding of a fundamentally different class of enzyme - proteases that reside immersed inside the membrane. This new field was the convergence of completely separate lines of research focused on cholesterol homeostasis, Alzheimer's disease, and developmental genetics. None intended their ultimate path, but soon became a richly-integrated fabric for an entirely new field: regulated intramembrane proteolysis. Our aim in this Special Issue is to focus on the ancient and nearly ubiquitous enzymes that catalyze this unexpected yet important reaction. The pace of progress has been dramatic, resulting in a rapidly-expanding universe of known cellular functions, and a paradigm shift in the biochemical understanding of these once heretical enzymes. More recently, the first therapeutic successes have been attained by targeting an intramembrane protease. We consider these advances and identify oncoming opportunities in four parts: growing spectra of cellular roles, insights into biochemical mechanisms, therapeutic strategies, and newly-emerging topics. Recent studies also expose challenges for the future, including non-linear relationships between substrate identification and physiological functions, and the need for potent and specific, not broad-class, inhibitors. © 2013.

  6. Mechanisms of cellular invasion by intracellular parasites.

    Science.gov (United States)

    Walker, Dawn M; Oghumu, Steve; Gupta, Gaurav; McGwire, Bradford S; Drew, Mark E; Satoskar, Abhay R

    2014-04-01

    Numerous disease-causing parasites must invade host cells in order to prosper. Collectively, such pathogens are responsible for a staggering amount of human sickness and death throughout the world. Leishmaniasis, Chagas disease, toxoplasmosis, and malaria are neglected diseases and therefore are linked to socio-economical and geographical factors, affecting well-over half the world's population. Such obligate intracellular parasites have co-evolved with humans to establish a complexity of specific molecular parasite-host cell interactions, forming the basis of the parasite's cellular tropism. They make use of such interactions to invade host cells as a means to migrate through various tissues, to evade the host immune system, and to undergo intracellular replication. These cellular migration and invasion events are absolutely essential for the completion of the lifecycles of these parasites and lead to their for disease pathogenesis. This review is an overview of the molecular mechanisms of protozoan parasite invasion of host cells and discussion of therapeutic strategies, which could be developed by targeting these invasion pathways. Specifically, we focus on four species of protozoan parasites Leishmania, Trypanosoma cruzi, Plasmodium, and Toxoplasma, which are responsible for significant morbidity and mortality.

  7. Discrete dynamic modeling of cellular signaling networks.

    Science.gov (United States)

    Albert, Réka; Wang, Rui-Sheng

    2009-01-01

    Understanding signal transduction in cellular systems is a central issue in systems biology. Numerous experiments from different laboratories generate an abundance of individual components and causal interactions mediating environmental and developmental signals. However, for many signal transduction systems there is insufficient information on the overall structure and the molecular mechanisms involved in the signaling network. Moreover, lack of kinetic and temporal information makes it difficult to construct quantitative models of signal transduction pathways. Discrete dynamic modeling, combined with network analysis, provides an effective way to integrate fragmentary knowledge of regulatory interactions into a predictive mathematical model which is able to describe the time evolution of the system without the requirement for kinetic parameters. This chapter introduces the fundamental concepts of discrete dynamic modeling, particularly focusing on Boolean dynamic models. We describe this method step-by-step in the context of cellular signaling networks. Several variants of Boolean dynamic models including threshold Boolean networks and piecewise linear systems are also covered, followed by two examples of successful application of discrete dynamic modeling in cell biology.

  8. Information theory based approaches to cellular signaling.

    Science.gov (United States)

    Waltermann, Christian; Klipp, Edda

    2011-10-01

    Cells interact with their environment and they have to react adequately to internal and external changes such changes in nutrient composition, physical properties like temperature or osmolarity and other stresses. More specifically, they must be able to evaluate whether the external change is significant or just in the range of noise. Based on multiple external parameters they have to compute an optimal response. Cellular signaling pathways are considered as the major means of information perception and transmission in cells. Here, we review different attempts to quantify information processing on the level of individual cells. We refer to Shannon entropy, mutual information, and informal measures of signaling pathway cross-talk and specificity. Information theory in systems biology has been successfully applied to identification of optimal pathway structures, mutual information and entropy as system response in sensitivity analysis, and quantification of input and output information. While the study of information transmission within the framework of information theory in technical systems is an advanced field with high impact in engineering and telecommunication, its application to biological objects and processes is still restricted to specific fields such as neuroscience, structural and molecular biology. However, in systems biology dealing with a holistic understanding of biochemical systems and cellular signaling only recently a number of examples for the application of information theory have emerged. This article is part of a Special Issue entitled Systems Biology of Microorganisms. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Probabilistic cellular automata: Some statistical mechanical considerations

    International Nuclear Information System (INIS)

    Lebowitz, J.L.; Maes, C.; Speer, E.R.

    1990-01-01

    Spin systems evolving in continuous or discrete time under the action of stochastic dynamics are used to model phenomena as diverse as the structure of alloys and the functioning of neural networks. While in some cases the dynamics are secondary, designed to produce a specific stationary measure whose properties one is interested in studying, there are other cases in which the only available information is the dynamical rule. Prime examples of the former are computer simulations, via Glauber dynamics, of equilibrium Gibbs measures with a specified interaction potential. Examples of the latter include various types of majority rule dynamics used as models for pattern recognition and for error-tolerant computations. The present note discusses ways in which techniques found useful in equilibrium statistical mechanics can be applied to a particular class of models of the latter types. These are cellular automata with noise: systems in which the spins are updated stochastically at integer times, simultaneously at all sites of some regular lattice. These models were first investigated in detail in the Soviet literature of the late sixties and early seventies. They are now generally referred to as Stochastic or Probabilistic Cellular Automata (PCA), and may be considered to include deterministic automata (CA) as special limits. 16 refs., 3 figs

  10. Cellular commitment in the developing cerebellum

    Science.gov (United States)

    Marzban, Hassan; Del Bigio, Marc R.; Alizadeh, Javad; Ghavami, Saeid; Zachariah, Robby M.; Rastegar, Mojgan

    2014-01-01

    The mammalian cerebellum is located in the posterior cranial fossa and is critical for motor coordination and non-motor functions including cognitive and emotional processes. The anatomical structure of cerebellum is distinct with a three-layered cortex. During development, neurogenesis and fate decisions of cerebellar primordium cells are orchestrated through tightly controlled molecular events involving multiple genetic pathways. In this review, we will highlight the anatomical structure of human and mouse cerebellum, the cellular composition of developing cerebellum, and the underlying gene expression programs involved in cell fate commitments in the cerebellum. A critical evaluation of the cell death literature suggests that apoptosis occurs in ~5% of cerebellar cells, most shortly after mitosis. Apoptosis and cellular autophagy likely play significant roles in cerebellar development, we provide a comprehensive discussion of their role in cerebellar development and organization. We also address the possible function of unfolded protein response in regulation of cerebellar neurogenesis. We discuss recent advancements in understanding the epigenetic signature of cerebellar compartments and possible connections between DNA methylation, microRNAs and cerebellar neurodegeneration. Finally, we discuss genetic diseases associated with cerebellar dysfunction and their role in the aging cerebellum. PMID:25628535

  11. Tension and robustness in multitasking cellular networks.

    Directory of Open Access Journals (Sweden)

    Jeffrey V Wong

    Full Text Available Cellular networks multitask by exhibiting distinct, context-dependent dynamics. However, network states (parameters that generate a particular dynamic are often sub-optimal for others, defining a source of "tension" between them. Though multitasking is pervasive, it is not clear where tension arises, what consequences it has, and how it is resolved. We developed a generic computational framework to examine the source and consequences of tension between pairs of dynamics exhibited by the well-studied RB-E2F switch regulating cell cycle entry. We found that tension arose from task-dependent shifts in parameters associated with network modules. Although parameter sets common to distinct dynamics did exist, tension reduced both their accessibility and resilience to perturbation, indicating a trade-off between "one-size-fits-all" solutions and robustness. With high tension, robustness can be preserved by dynamic shifting of modules, enabling the network to toggle between tasks, and by increasing network complexity, in this case by gene duplication. We propose that tension is a general constraint on the architecture and operation of multitasking biological networks. To this end, our work provides a framework to quantify the extent of tension between any network dynamics and how it affects network robustness. Such analysis would suggest new ways to interfere with network elements to elucidate the design principles of cellular networks.

  12. Filovirus tropism: Cellular molecules for viral entry

    Directory of Open Access Journals (Sweden)

    Ayato eTakada

    2012-02-01

    Full Text Available In human and nonhuman primates, filoviruses (Ebola and Marburg viruses cause severe hemorrhagic fever.Recently, other animals such as pigs and some species of fruit bats have also been shown to be susceptible to these viruses. While having a preference for some cell types such as hepatocytes, endothelial cells, dendritic cells, monocytes, and macrophages, filoviruses are known to be pantropic in infection of primates. The envelope glycoprotein (GP is responsible for both receptor binding and fusion of the virus envelope with the host cell membrane. It has been demonstrated that filovirus GP interacts with multiple molecules for entry into host cells, whereas none of the cellular molecules so far identified as a receptor/coreceptor fully explains filovirus tissue tropism and host range. Available data suggest that the mucin-like region (MLR on GP plays an important role in attachment to the preferred target cells, whose infection is likely involved in filovirus pathogenesis, whereas the MLR is not essential for the fundamental function of the GP in viral entry into cells in vitro. Further studies elucidating the mechanisms of cellular entry of filoviruses may shed light on the development of strategies for prophylaxis and treatment of Ebola and Marburg hemorrhagic fevers.

  13. Cellular Commitment in the Developing Cerebellum

    Directory of Open Access Journals (Sweden)

    Hassan eMarzban

    2015-01-01

    Full Text Available The mammalian cerebellum is located in the posterior cranial fossa and is critical for motor coordination and non-motor functions including cognitive and emotional processes. The anatomical structure of cerebellum is distinct with a three-layered cortex. During development, neurogenesis and fate decisions of cerebellar primordium cells are orchestrated through tightly controlled molecular events involving multiple genetic pathways. In this review, we will highlight the anatomical structure of human and mouse cerebellum, the cellular composition of developing cerebellum, and the underlying gene expression programs involved in cell fate commitments in the cerebellum. A critical evaluation of the cell death literature suggests that apoptosis occurs in ~5% of cerebellar cells, most shortly after mitosis. Apoptosis and cellular autophagy likely play significant roles in cerebellar development, we provide a comprehensive discussion of their role in cerebellar development and organization. We also address the possible function of unfolded protein response in regulation of cerebellar neurogenesis. We discuss recent advancements in understanding the epigenetic signature of cerebellar compartments and possible connections between DNA methylation, microRNAs and cerebellar neurodegeneration. Finally, we then discuss genetic diseases associated with cerebellar dysfunction and their role in the aging cerebellum.

  14. A Mathematical Model for Cisplatin Cellular Pharmacodynamics

    Directory of Open Access Journals (Sweden)

    Ardith W. El-Kareh

    2003-03-01

    Full Text Available A simple theoretical model for the cellular pharmacodynamics of cisplatin is presented. The model, which takes into account the kinetics of cisplatin uptake by cells and the intracellular binding of the drug, can be used to predict the dependence of survival (relative to controls on the time course of extracellular exposure. Cellular pharmacokinetic parameters are derived from uptake data for human ovarian and head and neck cancer cell lines. Survival relative to controls is assumed to depend on the peak concentration of DNA-bound intracellular platinum. Model predictions agree well with published data on cisplatin cytotoxicity for three different cancer cell lines, over a wide range of exposure times. In comparison with previously published mathematical models for anticancer drug pharmacodynamics, the present model provides a better fit to experimental data sets including long exposure times (∼100 hours. The model provides a possible explanation for the fact that cell kill correlates well with area under the extracellular concentration-time curve in some data sets, but not in others. The model may be useful for optimizing delivery schedules and for the dosing of cisplatin for cancer therapy.

  15. Health aspects of cellular mobile telephones

    International Nuclear Information System (INIS)

    Garn, H.

    1996-01-01

    Cellular mobile telephones are one of the main topics among health aspects of electromagnetic fields. In many countries, the number of people opposing communication towers is on the rise. Lawsuits against telecommunication and power line companies have been filed. All this makes people doubt the safety of electromagnetic fields. With respect to cellular phones, there are two scenarios: * Exposure of the operators of hand-held terminals (HHT). * Exposure of the general public from base stations (BS). In the first case, the transmit antenna of the HHT is very close to the human body. For normal operation, the distance will roughly be 2 - 3 cm. The transmitter power of the HHT is comparatively low, but there is a considerable fraction of the radiated electromagnetic energy penetrating the tissue. Considering the second case, BS transmitter powers are by a factor of 100-1000 higher, but the distance between antenna and the human body is by a factor of 1000-100,000 greater, as far as areas of unrestricted public access are concerned. As the power density of an electromagnetic wave decreases inversely proportional to the square of the distance, exposure of the public is always significantly (by many orders of magnitude) lower than exposure of operators of HHTs. Some well-known interaction mechanisms of microwave radiation with the human body have been very well-established today. In some other areas, there is still a need for further research. This paper summarizes present knowledge on human safety with mobile telephone systems. (author)

  16. Two Phase Flow Simulation Using Cellular Automata

    International Nuclear Information System (INIS)

    Marcel, C.P.

    2002-01-01

    The classical mathematical treatment of two-phase flows is based on the average of the conservation equations for each phase.In this work, a complementary approach to the modeling of these systems based on statistical population balances of aut omata sets is presented.Automata are entities defined by mathematical states that change following iterative rules representing interactions with the neighborhood.A model of automata for two-phase flow simulation is presented.This model consists of fie lds of virtual spheres that change their volumes and move around a certain environment.The model is more general than the classical cellular automata in two respects: the grid of cellular automata is dismissed in favor of a trajectory generator, and the rules of interaction involve parameters representing the actual physical interactions between phases.Automata simulation was used to study unsolved two-phase flow problems involving high heat flux rates. One system described in this work consists of a vertical channel with saturated water at normal pressure heated from the lower surface.The heater causes water to boil and starts the bubble production.We used cellular automata to describe two-phase flows and the interaction with the heater.General rule s for such cellular automata representing bubbles moving in stagnant liquid were used, with special attention to correct modeling of different mechanisms of heat transfer.The results of the model were compared to previous experiments and correlations finding good agreement.One of the most important findings is the confirmation of Kutateladze's idea about a close relation between the start of critical heat flux and a change in the flow's topology.This was analyzed using a control volume located in the upper surface of the heater.A strong decrease in the interfacial surface just before the CHF start was encountered.The automata describe quite well some characteristic parameters such as the shape of the local void fraction in the

  17. Recursive definition of global cellular-automata mappings

    DEFF Research Database (Denmark)

    Feldberg, Rasmus; Knudsen, Carsten; Rasmussen, Steen

    1994-01-01

    A method for a recursive definition of global cellular-automata mappings is presented. The method is based on a graphical representation of global cellular-automata mappings. For a given cellular-automaton rule the recursive algorithm defines the change of the global cellular-automaton mapping...... as the number of lattice sites is incremented. A proof of lattice size invariance of global cellular-automata mappings is derived from an approximation to the exact recursive definition. The recursive definitions are applied to calculate the fractal dimension of the set of reachable states and of the set...

  18. Toxicity of pyrolysis gases from some cellular polymers

    Science.gov (United States)

    Hilado, C. J.; Machado, A. M.

    1978-01-01

    Various samples of cellular polymers were evaluated for toxicity of pyrolysis gases, using the screening test method developed at the University of San Francisco. The cellular polymer samples included polyimide, polymethacrylimide, polybismaleimide, polyurethane, polyisocyanurate, polyethylene, polychloroprene, polyvinyl chloride, polystyrene, polysiloxane, and polyphosphazene. The cellular polymers exhibited varying levels of toxicity under these test conditions. Among the rigid cellular polymers, times to death were shortest with the imide type foams and longest with polyvinyl chloride and polystyrene. Among the flexible cellular polymers, times to death were shortest with polyimide and polyester, and longest with polychloroprene and polysiloxane. Increased char yield was not necessarily associated with reduced toxicity.

  19. Agent-Based Modeling of Mitochondria Links Sub-Cellular Dynamics to Cellular Homeostasis and Heterogeneity.

    Directory of Open Access Journals (Sweden)

    Giovanni Dalmasso

    Full Text Available Mitochondria are semi-autonomous organelles that supply energy for cellular biochemistry through oxidative phosphorylation. Within a cell, hundreds of mobile mitochondria undergo fusion and fission events to form a dynamic network. These morphological and mobility dynamics are essential for maintaining mitochondrial functional homeostasis, and alterations both impact and reflect cellular stress states. Mitochondrial homeostasis is further dependent on production (biogenesis and the removal of damaged mitochondria by selective autophagy (mitophagy. While mitochondrial function, dynamics, biogenesis and mitophagy are highly-integrated processes, it is not fully understood how systemic control in the cell is established to maintain homeostasis, or respond to bioenergetic demands. Here we used agent-based modeling (ABM to integrate molecular and imaging knowledge sets, and simulate population dynamics of mitochondria and their response to environmental energy demand. Using high-dimensional parameter searches we integrated experimentally-measured rates of mitochondrial biogenesis and mitophagy, and using sensitivity analysis we identified parameter influences on population homeostasis. By studying the dynamics of cellular subpopulations with distinct mitochondrial masses, our approach uncovered system properties of mitochondrial populations: (1 mitochondrial fusion and fission activities rapidly establish mitochondrial sub-population homeostasis, and total cellular levels of mitochondria alter fusion and fission activities and subpopulation distributions; (2 restricting the directionality of mitochondrial mobility does not alter morphology subpopulation distributions, but increases network transmission dynamics; and (3 maintaining mitochondrial mass homeostasis and responding to bioenergetic stress requires the integration of mitochondrial dynamics with the cellular bioenergetic state. Finally, (4 our model suggests sources of, and stress conditions

  20. Wireless traffic steering for green cellular networks

    CERN Document Server

    Zhang, Shan; Zhou, Sheng; Niu, Zhisheng; Shen, Xuemin (Sherman)

    2016-01-01

    This book introduces wireless traffic steering as a paradigm to realize green communication in multi-tier heterogeneous cellular networks. By matching network resources and dynamic mobile traffic demand, traffic steering helps to reduce on-grid power consumption with on-demand services provided. This book reviews existing solutions from the perspectives of energy consumption reduction and renewable energy harvesting. Specifically, it explains how traffic steering can improve energy efficiency through intelligent traffic-resource matching. Several promising traffic steering approaches for dynamic network planning and renewable energy demand-supply balancing are discussed. This book presents an energy-aware traffic steering method for networks with energy harvesting, which optimizes the traffic allocated to each cell based on the renewable energy status. Renewable energy demand-supply balancing is a key factor in energy dynamics, aimed at enhancing renewable energy sustainability to reduce on-grid energy consum...

  1. Nutritional education from Molecular and Cellular Biology

    Directory of Open Access Journals (Sweden)

    Zaida Ramona Betancourt Betancourt

    2014-12-01

    Full Text Available The nutritional education is current topic, constituting a necessity in the contemporary world, given mainly by the contribution that it makes in maintaining the human health under good conditions. Starting from this problem, it is presented this article whose objective is: to show the potential ities that the discipline Cellular and Molecular Biology offers, for the treatment of these contents, since this discipline is worked in the second semester of first year and first semester of in the formation of professors of the Biology - Geography and Bio logy - C hemistry careers which can contribute to the development of knowledge, habits and abilities that allows them to appropriate of responsible behaviours for the achievement of correct nutritional habits.

  2. Colonization of bone matrices by cellular components

    Science.gov (United States)

    Shchelkunova, E. I.; Voropaeva, A. A.; Korel, A. V.; Mayer, D. A.; Podorognaya, V. T.; Kirilova, I. A.

    2017-09-01

    Practical surgery, traumatology, orthopedics, and oncology require bioengineered constructs suitable for replacement of large-area bone defects. Only rigid/elastic matrix containing recipient's bone cells capable of mitosis, differentiation, and synthesizing extracellular matrix that supports cell viability can comply with these requirements. Therefore, the development of the techniques to produce structural and functional substitutes, whose three-dimensional structure corresponds to the recipient's damaged tissues, is the main objective of tissue engineering. This is achieved by developing tissue-engineering constructs represented by cells placed on the matrices. Low effectiveness of carrier matrix colonization with cells and their uneven distribution is one of the major problems in cell culture on various matrixes. In vitro studies of the interactions between cells and material, as well as the development of new techniques for scaffold colonization by cellular components are required to solve this problem.

  3. Stochastic properties of disturbed Elementary Cellular Automata

    International Nuclear Information System (INIS)

    Posiewnik, M.

    2005-01-01

    Cellular automata are class of simple mathematical systems that generate diverse, often complicated behaviour. Evolution of such a system is given by set of local and deterministic rules. However, in spite of simplicity of 'interactions' it's global behaviour can't be, in general, simply predicted or even can not be predicted in time shorter that time of it's strict evolution. We get as, a systems well known 1-dimensional, Wolfram class automata, and connect it into the reservoir consists of some random source (noise). In our experiment we are interested in: a) numeric verification of ergodicity for such a coupled system. b) finding it's probability distribution and evolution. c) finding some analogous for 'real' quantities and behaviour. d) using the dynamical systems and Markov chains theory to describe the system, and to make any predictions of it's behaviour. (author)

  4. Cellular imaging electron tomography and related techniques

    CERN Document Server

    2018-01-01

    This book highlights important techniques for cellular imaging and covers the basics and applications of electron tomography and related techniques. In addition, it considers practical aspects and broadens the technological focus by incorporating techniques that are only now becoming accessible (e.g. block face imaging).  The first part of the book describes the electron microscopy 3D technique available to scientists around the world, allowing them to characterize organelles, cells and tissues. The major emphasis is on new technologies like scanning transmission electron microscopy (STEM) tomography, though the book also reviews some of the more proven technologies like electron tomography. In turn, the second part is dedicated to the reconstruction of data sets, signal improvement and interpretation.

  5. Determining Lineage Pathways from Cellular Barcoding Experiments

    Directory of Open Access Journals (Sweden)

    Leïla Perié

    2014-02-01

    Full Text Available Cellular barcoding and other single-cell lineage-tracing strategies form experimental methodologies for analysis of in vivo cell fate that have been instrumental in several significant recent discoveries. Due to the highly nonlinear nature of proliferation and differentiation, interrogation of the resulting data for evaluation of potential lineage pathways requires a new quantitative framework complete with appropriate statistical tests. Here, we develop such a framework, illustrating its utility by analyzing data from barcoded multipotent cells of the blood system. This application demonstrates that the data require additional paths beyond those found in the classical model, which leads us to propose that hematopoietic differentiation follows a loss of potential mechanism and to suggest further experiments to test this deduction. Our quantitative framework can evaluate the compatibility of lineage trees with barcoded data from any proliferating and differentiating cell system.

  6. Cellular energy metabolism in T-lymphocytes.

    Science.gov (United States)

    Gaber, Timo; Strehl, Cindy; Sawitzki, Birgit; Hoff, Paula; Buttgereit, Frank

    2015-01-01

    Energy homeostasis is a hallmark of cell survival and maintenance of cell function. Here we focus on the impact of cellular energy metabolism on T-lymphocyte differentiation, activation, and function in health and disease. We describe the role of transcriptional and posttranscriptional regulation of lymphocyte metabolism on immune functions of T cells. We also summarize the current knowledge about T-lymphocyte adaptations to inflammation and hypoxia, and the impact on T-cell behavior of pathophysiological hypoxia (as found in tumor tissue, chronically inflamed joints in rheumatoid arthritis and during bone regeneration). A better understanding of the underlying mechanisms that control immune cell metabolism and immune response may provide therapeutic opportunities to alter the immune response under conditions of either immunosuppression or inflammation, potentially targeting infections, vaccine response, tumor surveillance, autoimmunity, and inflammatory disorders.

  7. Computing by Temporal Order: Asynchronous Cellular Automata

    Directory of Open Access Journals (Sweden)

    Michael Vielhaber

    2012-08-01

    Full Text Available Our concern is the behaviour of the elementary cellular automata with state set 0,1 over the cell set Z/nZ (one-dimensional finite wrap-around case, under all possible update rules (asynchronicity. Over the torus Z/nZ (n<= 11,we will see that the ECA with Wolfram rule 57 maps any v in F_2^n to any w in F_2^n, varying the update rule. We furthermore show that all even (element of the alternating group bijective functions on the set F_2^n = 0,...,2^n-1, can be computed by ECA57, by iterating it a sufficient number of times with varying update rules, at least for n <= 10. We characterize the non-bijective functions computable by asynchronous rules.

  8. Particles and Patterns in Cellular Automata

    International Nuclear Information System (INIS)

    Jen, E.; Das, R.; Beasley, C.E.

    1999-01-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Our objective has been to develop tools for studying particle interactions in a class of dynamical systems characterized by discreteness, determinism, local interaction, and an inherently parallel form of evolution. These systems can be described by cellular automata (CA) and the behavior we studied has improved our understanding of the nature of patterns generated by CAs, their ability to perform global computations, and their relationship to continuous dynamical systems. We have also developed a rule-table mathematics that enables one to custom-design CA rule tables to generate patterns of specified types, or to perform specified computational tasks

  9. Simulation of earthquakes with cellular automata

    Directory of Open Access Journals (Sweden)

    P. G. Akishin

    1998-01-01

    Full Text Available The relation between cellular automata (CA models of earthquakes and the Burridge–Knopoff (BK model is studied. It is shown that the CA proposed by P. Bak and C. Tang,although they have rather realistic power spectra, do not correspond to the BK model. We present a modification of the CA which establishes the correspondence with the BK model.An analytical method of studying the evolution of the BK-like CA is proposed. By this method a functional quadratic in stress release, which can be regarded as an analog of the event energy, is constructed. The distribution of seismic events with respect to this “energy” shows rather realistic behavior, even in two dimensions. Special attention is paid to two-dimensional automata; the physical restrictions on compression and shear stiffnesses are imposed.

  10. Mathematical analysis of complex cellular activity

    CERN Document Server

    Bertram, Richard; Teka, Wondimu; Vo, Theodore; Wechselberger, Martin; Kirk, Vivien; Sneyd, James

    2015-01-01

    This book contains two review articles on mathematical physiology that deal with closely related topics but were written and can be read independently. The first article reviews the basic theory of calcium oscillations (common to almost all cell types), including spatio-temporal behaviors such as waves. The second article uses, and expands on, much of this basic theory to show how the interaction of cytosolic calcium oscillators with membrane ion channels can result in highly complex patterns of electrical spiking. Through these examples one can see clearly how multiple oscillatory processes interact within a cell, and how mathematical methods can be used to understand such interactions better. The two reviews provide excellent examples of how mathematics and physiology can learn from each other, and work jointly towards a better understanding of complex cellular processes. Review 1: Richard Bertram, Joel Tabak, Wondimu Teka, Theodore Vo, Martin Wechselberger: Geometric Singular Perturbation Analysis of Burst...

  11. Molecular and cellular endocrinology of the testis

    International Nuclear Information System (INIS)

    Stefanini, M.; Conti, M.; Geremia, R.; Ziparo, E.

    1986-01-01

    This volume contains the Proceedings of the IV European Workshop on Molecular and Cellular Endocrinology of the Testis held in Capri (Italy) between the 9th and 12th April 1986. The workshop was organized in several symposia related to some of the most relevant aspects of the regulation of testicular function. Main topics were the role of cell interactions, the mechanisms of signal transduction, gene expression and metabolic response of somatic cells as well as differentiation of germ cells. One session was devoted to prostaglandins in the male reproductive system and to brief discussions on interstitial fluid and on antispermatogenic compounds. In this book only the main lectures and some selected short papers are presented. (Auth.)

  12. Biological (molecular and cellular) markers of toxicity

    International Nuclear Information System (INIS)

    Shugart, L.R.; D'Surney, S.J.; Gettys-Hull, C.; Greeley, M.S. Jr.

    1991-01-01

    Several molecular and cellular markers of genotoxicity were adapted for measurement in the Medaka (Oryzias latipes), and were used to describe the effects of treatment of the organism with diethylnitrosamine (DEN). NO 6 -ethyl guanine adducts were detected, and a slight statistically significant, increase in DNA strand breaks was observed. These results are consistent with the hypothesis that prolonged exposure to high levels of DEN induced alkyltransferase activity which enzymatically removes any O 6 -ethyl guanine adducts but does not result in strand breaks or hypomethylation of the DNA such as might be expected from excision repair of chemically modified DNA. Following a five week continuous DEN exposure with 100 percent renewal of DEN-water every third day, the F values (DNA double strandedness) increased considerably and to similar extent in fish exposed to 25, 50, and 100 ppM DEN. This has been observed also in medaka exposed to BaP

  13. Cellular telephone-based radiation detection instrument

    Science.gov (United States)

    Craig, William W [Pittsburg, CA; Labov, Simon E [Berkeley, CA

    2011-06-14

    A network of radiation detection instruments, each having a small solid state radiation sensor module integrated into a cellular phone for providing radiation detection data and analysis directly to a user. The sensor module includes a solid-state crystal bonded to an ASIC readout providing a low cost, low power, light weight compact instrument to detect and measure radiation energies in the local ambient radiation field. In particular, the photon energy, time of event, and location of the detection instrument at the time of detection is recorded for real time transmission to a central data collection/analysis system. The collected data from the entire network of radiation detection instruments are combined by intelligent correlation/analysis algorithms which map the background radiation and detect, identify and track radiation anomalies in the region.

  14. Cellular and chemical neuroscience of mammalian sleep.

    Science.gov (United States)

    Datta, Subimal

    2010-05-01

    Extraordinary strides have been made toward understanding the complexities and regulatory mechanisms of sleep over the past two decades thanks to the help of rapidly evolving technologies. At its most basic level, mammalian sleep is a restorative process of the brain and body. Beyond its primary restorative purpose, sleep is essential for a number of vital functions. Our primary research interest is to understand the cellular and molecular mechanisms underlying the regulation of sleep and its cognitive functions. Here I will reflect on our own research contributions to 50 years of extraordinary advances in the neurobiology of slow-wave sleep (SWS) and rapid eye movement (REM) sleep regulation. I conclude this review by suggesting some potential future directions to further our understanding of the neurobiology of sleep. Copyright 2010 Elsevier B.V. All rights reserved.

  15. Cellular and Molecular Targets of Menthol Actions

    Directory of Open Access Journals (Sweden)

    Murat Oz

    2017-07-01

    Full Text Available Menthol belongs to monoterpene class of a structurally diverse group of phytochemicals found in plant-derived essential oils. Menthol is widely used in pharmaceuticals, confectionary, oral hygiene products, pesticides, cosmetics, and as a flavoring agent. In addition, menthol is known to have antioxidant, anti-inflammatory, and analgesic effects. Recently, there has been renewed awareness in comprehending the biological and pharmacological effects of menthol. TRP channels have been demonstrated to mediate the cooling actions of menthol. There has been new evidence demonstrating that menthol can significantly influence the functional characteristics of a number of different kinds of ligand and voltage-gated ion channels, indicating that at least some of the biological and pharmacological effects of menthol can be mediated by alterations in cellular excitability. In this article, we examine the results of earlier studies on the actions of menthol with voltage and ligand-gated ion channels.

  16. Simulating Complex Systems by Cellular Automata

    CERN Document Server

    Kroc, Jiri; Hoekstra, Alfons G

    2010-01-01

    Deeply rooted in fundamental research in Mathematics and Computer Science, Cellular Automata (CA) are recognized as an intuitive modeling paradigm for Complex Systems. Already very basic CA, with extremely simple micro dynamics such as the Game of Life, show an almost endless display of complex emergent behavior. Conversely, CA can also be designed to produce a desired emergent behavior, using either theoretical methodologies or evolutionary techniques. Meanwhile, beyond the original realm of applications - Physics, Computer Science, and Mathematics – CA have also become work horses in very different disciplines such as epidemiology, immunology, sociology, and finance. In this context of fast and impressive progress, spurred further by the enormous attraction these topics have on students, this book emerges as a welcome overview of the field for its practitioners, as well as a good starting point for detailed study on the graduate and post-graduate level. The book contains three parts, two major parts on th...

  17. Cellular and molecular mechanisms coordinating pancreas development.

    Science.gov (United States)

    Bastidas-Ponce, Aimée; Scheibner, Katharina; Lickert, Heiko; Bakhti, Mostafa

    2017-08-15

    The pancreas is an endoderm-derived glandular organ that participates in the regulation of systemic glucose metabolism and food digestion through the function of its endocrine and exocrine compartments, respectively. While intensive research has explored the signaling pathways and transcriptional programs that govern pancreas development, much remains to be discovered regarding the cellular processes that orchestrate pancreas morphogenesis. Here, we discuss the developmental mechanisms and principles that are known to underlie pancreas development, from induction and lineage formation to morphogenesis and organogenesis. Elucidating such principles will help to identify novel candidate disease genes and unravel the pathogenesis of pancreas-related diseases, such as diabetes, pancreatitis and cancer. © 2017. Published by The Company of Biologists Ltd.

  18. A cellular automata model of bone formation.

    Science.gov (United States)

    Van Scoy, Gabrielle K; George, Estee L; Opoku Asantewaa, Flora; Kerns, Lucy; Saunders, Marnie M; Prieto-Langarica, Alicia

    2017-04-01

    Bone remodeling is an elegantly orchestrated process by which osteocytes, osteoblasts and osteoclasts function as a syncytium to maintain or modify bone. On the microscopic level, bone consists of cells that create, destroy and monitor the bone matrix. These cells interact in a coordinated manner to maintain a tightly regulated homeostasis. It is this regulation that is responsible for the observed increase in bone gain in the dominant arm of a tennis player and the observed increase in bone loss associated with spaceflight and osteoporosis. The manner in which these cells interact to bring about a change in bone quality and quantity has yet to be fully elucidated. But efforts to understand the multicellular complexity can ultimately lead to eradication of metabolic bone diseases such as osteoporosis and improved implant longevity. Experimentally validated mathematical models that simulate functional activity and offer eventual predictive capabilities offer tremendous potential in understanding multicellular bone remodeling. Here we undertake the initial challenge to develop a mathematical model of bone formation validated with in vitro data obtained from osteoblastic bone cells induced to mineralize and quantified at 26 days of culture. A cellular automata model was constructed to simulate the in vitro characterization. Permutation tests were performed to compare the distribution of the mineralization in the cultures and the distribution of the mineralization in the mathematical models. The results of the permutation test show the distribution of mineralization from the characterization and mathematical model come from the same probability distribution, therefore validating the cellular automata model. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Complex cellular logic computation using ribocomputing devices.

    Science.gov (United States)

    Green, Alexander A; Kim, Jongmin; Ma, Duo; Silver, Pamela A; Collins, James J; Yin, Peng

    2017-08-03

    Synthetic biology aims to develop engineering-driven approaches to the programming of cellular functions that could yield transformative technologies. Synthetic gene circuits that combine DNA, protein, and RNA components have demonstrated a range of functions such as bistability, oscillation, feedback, and logic capabilities. However, it remains challenging to scale up these circuits owing to the limited number of designable, orthogonal, high-performance parts, the empirical and often tedious composition rules, and the requirements for substantial resources for encoding and operation. Here, we report a strategy for constructing RNA-only nanodevices to evaluate complex logic in living cells. Our 'ribocomputing' systems are composed of de-novo-designed parts and operate through predictable and designable base-pairing rules, allowing the effective in silico design of computing devices with prescribed configurations and functions in complex cellular environments. These devices operate at the post-transcriptional level and use an extended RNA transcript to co-localize all circuit sensing, computation, signal transduction, and output elements in the same self-assembled molecular complex, which reduces diffusion-mediated signal losses, lowers metabolic cost, and improves circuit reliability. We demonstrate that ribocomputing devices in Escherichia coli can evaluate two-input logic with a dynamic range up to 900-fold and scale them to four-input AND, six-input OR, and a complex 12-input expression (A1 AND A2 AND NOT A1*) OR (B1 AND B2 AND NOT B2*) OR (C1 AND C2) OR (D1 AND D2) OR (E1 AND E2). Successful operation of ribocomputing devices based on programmable RNA interactions suggests that systems employing the same design principles could be implemented in other host organisms or in extracellular settings.

  20. Modems for emerging digital cellular-mobile radio system

    Science.gov (United States)

    Feher, Kamilo

    1991-01-01

    Digital modem techniques for emerging digital cellular telecommunications-mobile radio system applications are described and analyzed. In particular, theoretical performance, experimental results, principles of operation, and various architectures of pi/4-QPSK (pi/4-shifted coherent or differential QPSK) modems for second-generation US digital cellular radio system applications are presented. The spectral/power efficiency and performance of the pi/4-QPSK modems (American and Japanese digital cellular emerging standards) are studied and briefly compared to GMSK (Gaussian minimum-shift keying) modems (proposed for European DECT and GSM cellular standards). Improved filtering strategies and digital pilot-aided (digital channel sounding) techniques are also considered for pi/4-QPSK and other digital modems. These techniques could significantly improve the performance of digital cellular and other digital land mobile and satellite mobile radio systems. More spectrally efficient modem trends for future cellular/mobile (land mobile) and satellite communication systems applications are also highlighted.

  1. 1,4-Naphthoquinones: From Oxidative Damage to Cellular and Inter-Cellular Signaling

    Directory of Open Access Journals (Sweden)

    Lars-Oliver Klotz

    2014-09-01

    Full Text Available Naphthoquinones may cause oxidative stress in exposed cells and, therefore, affect redox signaling. Here, contributions of redox cycling and alkylating properties of quinones (both natural and synthetic, such as plumbagin, juglone, lawsone, menadione, methoxy-naphthoquinones, and others to cellular and inter-cellular signaling processes are discussed: (i naphthoquinone-induced Nrf2-dependent modulation of gene expression and its potentially beneficial outcome; (ii the modulation of receptor tyrosine kinases, such as the epidermal growth factor receptor by naphthoquinones, resulting in altered gap junctional intercellular communication. Generation of reactive oxygen species and modulation of redox signaling are properties of naphthoquinones that render them interesting leads for the development of novel compounds of potential use in various therapeutic settings.

  2. Molecular and cellular neurocardiology: development, and cellular and molecular adaptations to heart disease

    Science.gov (United States)

    Anderson, Mark E.; Birren, Susan J.; Fukuda, Keiichi; Herring, Neil; Hoover, Donald B.; Kanazawa, Hideaki; Paterson, David J.; Ripplinger, Crystal M.

    2016-01-01

    Abstract The nervous system and cardiovascular system develop in concert and are functionally interconnected in both health and disease. This white paper focuses on the cellular and molecular mechanisms that underlie neural–cardiac interactions during development, during normal physiological function in the mature system, and during pathological remodelling in cardiovascular disease. The content on each subject was contributed by experts, and we hope that this will provide a useful resource for newcomers to neurocardiology as well as aficionados. PMID:27060296

  3. Performance Evaluation Of Mobile Cellular Networks In Nigeria

    OpenAIRE

    Shoewu, O.O

    2018-01-01

    The aim of this paper is to evaluate the performance of mobile networks such as MTN, GLO, and ETISALAT in Nigeria and suggest ways the performance of digital cellular networks can improve to minimize some of its present short comings or limitations. This paper discusses the performance improvement of digital cellular networks. A non- CDMA cellular network is use in an overall wireless environment for the purpose of this paper. This paper also discusses the performance assessment of three mobi...

  4. Cellular-automata supercomputers for fluid-dynamics modeling

    International Nuclear Information System (INIS)

    Margolus, N.; Toffoli, T.; Vichniac, G.

    1986-01-01

    We report recent developments in the modeling of fluid dynamics, and give experimental results (including dynamical exponents) obtained using cellular automata machines. Because of their locality and uniformity, cellular automata lend themselves to an extremely efficient physical realization; with a suitable architecture, an amount of hardware resources comparable to that of a home computer can achieve (in the simulation of cellular automata) the performance of a conventional supercomputer

  5. Cellular structures in a system of interacting particles

    International Nuclear Information System (INIS)

    Lev, B.I.

    2009-01-01

    The general description of the formation of a cellular structure in the system of interacting particles is proposed. The analytical results for possible cellular structures in the usual colloidal systems, systems of particles immersed in a liquid crystal, and gravitational systems have been presented. It is shown that the formation of a cellular structure in all systems of interacting particles at different temperatures and concentrations of particles has the same physical nature

  6. Iron Oxide Nanoparticles Stimulates Extra-Cellular Matrix Production in Cellular Spheroids

    Directory of Open Access Journals (Sweden)

    Megan Casco

    2017-01-01

    Full Text Available Nanotechnologies have been integrated into drug delivery, and non-invasive imaging applications, into nanostructured scaffolds for the manipulation of cells. The objective of this work was to determine how the physico-chemical properties of magnetic nanoparticles (MNPs and their spatial distribution into cellular spheroids stimulated cells to produce an extracellular matrix (ECM. The MNP concentration (0.03 mg/mL, 0.1 mg/mL and 0.3 mg/mL, type (magnetoferritin, shape (nanorod—85 nm × 425 nm and incorporation method were studied to determine each of their effects on the specific stimulation of four ECM proteins (collagen I, collagen IV, elastin and fibronectin in primary rat aortic smooth muscle cell. Results demonstrated that as MNP concentration increased there was up to a 6.32-fold increase in collagen production over no MNP samples. Semi-quantitative Immunohistochemistry (IHC results demonstrated that MNP type had the greatest influence on elastin production with a 56.28% positive area stain compared to controls and MNP shape favored elastin stimulation with a 50.19% positive area stain. Finally, there are no adverse effects of MNPs on cellular contractile ability. This study provides insight on the stimulation of ECM production in cells and tissues, which is important because it plays a critical role in regulating cellular functions.

  7. Validation of self-reported cellular phone use

    DEFF Research Database (Denmark)

    Samkange-Zeeb, Florence; Berg, Gabriele; Blettner, Maria

    2004-01-01

    BACKGROUND: In recent years, concern has been raised over possible adverse health effects of cellular telephone use. In epidemiological studies of cancer risk associated with the use of cellular telephones, the validity of self-reported cellular phone use has been problematic. Up to now there is ......BACKGROUND: In recent years, concern has been raised over possible adverse health effects of cellular telephone use. In epidemiological studies of cancer risk associated with the use of cellular telephones, the validity of self-reported cellular phone use has been problematic. Up to now...... there is very little information published on this subject. METHODS: We conducted a study to validate the questionnaire used in an ongoing international case-control study on cellular phone use, the "Interphone study". Self-reported cellular phone use from 68 of 104 participants who took part in our study...... was compared with information derived from the network providers over a period of 3 months (taken as the gold standard). RESULTS: Using Spearman's rank correlation, the correlation between self-reported phone use and information from the network providers for cellular phone use in terms of the number of calls...

  8. Cellular targets of inhalational anaesthetic- and opioid receptor ...

    African Journals Online (AJOL)

    Secondly, the cardioprotective effects occur independently of the ... cardioprotection take place and highlights the cellular ... Activation of sarcolemmal KATP channels hyperpolarizes cells, ..... respiration and its supramolecular organization.

  9. Design, synthesis and cellular metabolism study of 4'-selenonucleosides.

    Science.gov (United States)

    Yu, Jinha; Sahu, Pramod K; Kim, Gyudong; Qu, Shuhao; Choi, Yoojin; Song, Jayoung; Lee, Sang Kook; Noh, Minsoo; Park, Sunghyouk; Jeong, Lak Shin

    2015-01-01

    4'-seleno-homonucleosides were synthesized as next-generation nucleosides, and their cellular phosphorylation was studied to confirm the hypothesis that bulky selenium atom can sterically hinder the approach of cellular nucleoside kinase to the 5'-OH for phosphorylation. 4'-seleno-homonucleosides (n = 2), with one-carbon homologation, were synthesized through a tandem seleno-Michael addition-SN2 ring cyclization. LC-MS analysis demonstrated that they were phosphorylated by cellular nucleoside kinases, resulting in anticancer activity. The bulky selenium atom played a key role in deciding the phosphorylation by cellular nucleoside kinases. [Formula: see text].

  10. Multidimensional traveling waves in the Allen–Cahn cellular automaton

    International Nuclear Information System (INIS)

    Murata, Mikio

    2015-01-01

    Ultradiscretization is a limiting procedure transforming a given difference equation into a cellular automaton. The cellular automaton constructed by this procedure preserves the essential properties of the original equation, such as the structure of exact solutions for integrable equations. In this article, a cellular automaton analog of the multidimensional Allen–Cahn equation which is not an integrable system is constructed by the ultradiscretization. Moreover, the traveling wave solutions for the resulting cellular automaton are given. The shape, behavior and stability of the solutions in ultradiscrete systems are similar to those in continuous systems. (paper)

  11. Some Properties of topological pressure on cellular automata

    Directory of Open Access Journals (Sweden)

    Chih-Hung Chang

    2014-09-01

    Full Text Available This paper investigates the ergodicity and the power rule of the topological pressure of a cellular automaton. If a cellular automaton is either leftmost or rightmost premutive (due to the terminology given by Hedlund [Math.~Syst.~Theor.~3, 320-375, 1969], then it is ergodic with respect to the uniform Bernoulli measure. More than that, the relation of topological pressure between the original cellular automaton and its power rule is expressed in a closed form. As an application, the topological pressure of a linear cellular automaton can be computed explicitly.

  12. Movies of cellular and sub-cellular motion by digital holographic microscopy

    Directory of Open Access Journals (Sweden)

    Yu Lingfeng

    2006-03-01

    Full Text Available Abstract Background Many biological specimens, such as living cells and their intracellular components, often exhibit very little amplitude contrast, making it difficult for conventional bright field microscopes to distinguish them from their surroundings. To overcome this problem phase contrast techniques such as Zernike, Normarsky and dark-field microscopies have been developed to improve specimen visibility without chemically or physically altering them by the process of staining. These techniques have proven to be invaluable tools for studying living cells and furthering scientific understanding of fundamental cellular processes such as mitosis. However a drawback of these techniques is that direct quantitative phase imaging is not possible. Quantitative phase imaging is important because it enables determination of either the refractive index or optical thickness variations from the measured optical path length with sub-wavelength accuracy. Digital holography is an emergent phase contrast technique that offers an excellent approach in obtaining both qualitative and quantitative phase information from the hologram. A CCD camera is used to record a hologram onto a computer and numerical methods are subsequently applied to reconstruct the hologram to enable direct access to both phase and amplitude information. Another attractive feature of digital holography is the ability to focus on multiple focal planes from a single hologram, emulating the focusing control of a conventional microscope. Methods A modified Mach-Zender off-axis setup in transmission is used to record and reconstruct a number of holographic amplitude and phase images of cellular and sub-cellular features. Results Both cellular and sub-cellular features are imaged with sub-micron, diffraction-limited resolution. Movies of holographic amplitude and phase images of living microbes and cells are created from a series of holograms and reconstructed with numerically adjustable

  13. A Channel Allocation Mechanism for Cellular Networks

    Directory of Open Access Journals (Sweden)

    Chi-Hua Chen

    2017-04-01

    Full Text Available In cellular networks, call blocking causes lower customer satisfaction and economic loss. Therefore, the channel allocation for call block avoidance is an important issue. This study proposes a mechanism that considers the real-time traffic information (e.g., traffic flow and vehicle speed and the user behavior (e.g., call inter-arrival time and call holding time to analyze the adaptable number of communication calls in the specific cell for channel allocation. In experiments about call block probabilities (CBP, this study simulated two cases that are the situations of the whole day and traffic accident. The simulation results show that all CBPs in the scenario of whole day are less than 21.5% by using the proposed mechanism, which is better than using the static channel allocation (SCA mechanism. Moreover, all CBPs in the scenario of traffic accidents are less than 16.5% by using the proposed mechanism, which is better than using the SCA mechanism. Therefore, the proposed mechanism can decrease the number of CBPs effectively.

  14. Cooperative Handover Management in Dense Cellular Networks

    KAUST Repository

    Arshad, Rabe

    2017-02-07

    Network densification has always been an important factor to cope with the ever increasing capacity demand. Deploying more base stations (BSs) improves the spatial frequency utilization, which increases the network capacity. However, such improvement comes at the expense of shrinking the BSs\\' footprints, which increases the handover (HO) rate and may diminish the foreseen capacity gains. In this paper, we propose a cooperative HO management scheme to mitigate the HO effect on throughput gains achieved via cellular network densification. The proposed HO scheme relies on skipping HO to the nearest BS at some instances along the user\\'s trajectory while enabling cooperative BS service during HO execution at other instances. To this end, we develop a mathematical model, via stochastic geometry, to quantify the performance of the proposed HO scheme in terms of coverage probability and user throughput. The results show that the proposed cooperative HO scheme outperforms the always best connected based association at high mobility. Also, the value of BS cooperation along with handover skipping is quantified with respect to the HO skipping only that has recently appeared in the literature. Particularly, the proposed cooperative HO scheme shows throughput gains of 12% to 27% and 17% on average, when compared to the always best connected and HO skipping only schemes at user velocity ranging from 80 km/h to 160 Km/h, respectively.

  15. Cellular anomalies underlying retinoid-induced phocomelia.

    Science.gov (United States)

    Zhou, Jian; Kochhar, Devendra M

    2004-11-01

    The question of how alterations in cell behavior produced by retinoic acid (RA) influenced the development of skeletogenic mesenchyme of the limb bud was examined in this study. Our established model was employed, which involves treatment of pregnant mice with a teratogenic dose of RA (100 mg/kg) on 11 days postcoitum (dpc) resulting in a severe truncation of all long bones of the forelimbs in virtually every exposed fetus. It is shown that RA, administered at a stage to induce phocomelia in virtually all exposed embryos, resulted in immediate appearance of enhanced cell death within the mesenchyme in the central core of the limb bud, an area destined for chondrogenesis. The central core mesenchyme, which in the untreated limb buds experiences a sharp decline in cell proliferation heralding the onset of chondrogenesis, demonstrated a reversal of the process; this mesenchyme maintained a higher rate of cell proliferation upon RA exposure. These events resulted in a truncation and disorganization of the chondrogenic anlage, more pronounced in zeugopodal mesenchyme than in the autopod. We conclude that an inhibition of chondrogenesis was secondary to a disruption in cellular behavior caused by RA, a likely consequence of misregulation in the growth factor signaling cascade.

  16. Cellular mechanisms in drug - radiation interaction

    International Nuclear Information System (INIS)

    Trott, K.R.

    1979-01-01

    Some cytotoxic drugs, especially those belonging to the group of antibiotics and antimetabolites, sensitize the cells having survived drug treatment to the subsequent irradiation by either increasing the slope of the radiation dose response curves or by decreasing extrapolation number. Bleomycin was found to interact with radiation in L-cells and FM3A cells, but not in HeLa-cells. The data with EMT-6 cells suggest that the interaction depends on drug dose: no interaction occurred after the exposure to bleomycin which killed only 20 - 40% of the cells; yet the exposure to bleomycin which killed 90% of the cells in addition sensitized the surviving cells by the DMF of 1.3. The sensitization found 24 hr after the exposure of HeLa cells to methotrexate was due to cell synchronization. Other cytostatic drugs were found to synchronize proliferating cells even better. Therefore, the fluctuation of radiosensitivity has been commonly observed after the termination of exposure to these drugs. Preirradiation may lead to the change in drug dose response curves. The recruitment of resting cells into cycle occurs hours or days later, in some irradiated normal and malignant tissues. Since many cytostatic drugs are far more active in proliferating cells than in resting cells, the recruitment after irradiation may lead to the sudden increase in drug sensitivity, days after the irradiation. No single, simple theory seems to exist to classify and predict the cellular response to combined modality treatment. (Yamashita, S.)

  17. The cellular receptors of exogenous RNA

    Directory of Open Access Journals (Sweden)

    Patryk Reniewicz

    2016-04-01

    Full Text Available One of the key determinants of survival for organisms is proper recognition of exogenous and endogenous nucleic acids. Therefore, high eukaryotes developed a number of receptors that allow for discrimination between friend or foe DNA and RNA. Appearance of exogenous RNA in cytoplasm provides a signal of danger and triggers cellular responses that facilitate eradication of a pathogen. Recognition of exogenous RNA is additionally complicated by fact that large amount of endogenous RNA is present in cytoplasm Thus, number of different receptors, found in eukaryotic cells, is able to recognize that nucleic acid. First group of those receptors consist endosomal Toll like receptors, namely TLR3, TLR7, TLR8 and TLR13. Those receptors recognize RNA released from pathogens that enter the cell by endocytosis. The second group includes cytoplasmic sensors like PKR and the family of RLRs comprised of RIG-I, MDA5 and LGP2. Cytoplasmic receptors recognize RNA from pathogens invading the cell by non-endocytic pathway. In both cases binding of RNA by its receptors results in activation of the signalling cascades that lead to the production of interferon and other cytokines.

  18. Cooperative Handover Management in Dense Cellular Networks

    KAUST Repository

    Arshad, Rabe; Elsawy, Hesham; Sorour, Sameh; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2017-01-01

    Network densification has always been an important factor to cope with the ever increasing capacity demand. Deploying more base stations (BSs) improves the spatial frequency utilization, which increases the network capacity. However, such improvement comes at the expense of shrinking the BSs' footprints, which increases the handover (HO) rate and may diminish the foreseen capacity gains. In this paper, we propose a cooperative HO management scheme to mitigate the HO effect on throughput gains achieved via cellular network densification. The proposed HO scheme relies on skipping HO to the nearest BS at some instances along the user's trajectory while enabling cooperative BS service during HO execution at other instances. To this end, we develop a mathematical model, via stochastic geometry, to quantify the performance of the proposed HO scheme in terms of coverage probability and user throughput. The results show that the proposed cooperative HO scheme outperforms the always best connected based association at high mobility. Also, the value of BS cooperation along with handover skipping is quantified with respect to the HO skipping only that has recently appeared in the literature. Particularly, the proposed cooperative HO scheme shows throughput gains of 12% to 27% and 17% on average, when compared to the always best connected and HO skipping only schemes at user velocity ranging from 80 km/h to 160 Km/h, respectively.

  19. [Stress-induced cellular adaptive mutagenesis].

    Science.gov (United States)

    Zhu, Linjiang; Li, Qi

    2014-04-01

    The adaptive mutations exist widely in the evolution of cells, such as antibiotic resistance mutations of pathogenic bacteria, adaptive evolution of industrial strains, and cancerization of human somatic cells. However, how these adaptive mutations are generated is still controversial. Based on the mutational analysis models under the nonlethal selection conditions, stress-induced cellular adaptive mutagenesis is proposed as a new evolutionary viewpoint. The hypothetic pathway of stress-induced mutagenesis involves several intracellular physiological responses, including DNA damages caused by accumulation of intracellular toxic chemicals, limitation of DNA MMR (mismatch repair) activity, upregulation of general stress response and activation of SOS response. These responses directly affect the accuracy of DNA replication from a high-fidelity manner to an error-prone one. The state changes of cell physiology significantly increase intracellular mutation rate and recombination activity. In addition, gene transcription under stress condition increases the instability of genome in response to DNA damage, resulting in transcription-associated DNA mutagenesis. In this review, we summarize these two molecular mechanisms of stress-induced mutagenesis and transcription-associated DNA mutagenesis to help better understand the mechanisms of adaptive mutagenesis.

  20. Cellular Aspects of Prion Replication In Vitro

    Science.gov (United States)

    Grassmann, Andrea; Wolf, Hanna; Hofmann, Julia; Graham, James; Vorberg, Ina

    2013-01-01

    Prion diseases or transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative disorders in mammals that are caused by unconventional agents predominantly composed of aggregated misfolded prion protein (PrP). Prions self-propagate by recruitment of host-encoded PrP into highly ordered β-sheet rich aggregates. Prion strains differ in their clinical, pathological and biochemical characteristics and are likely to be the consequence of distinct abnormal prion protein conformers that stably replicate their alternate states in the host cell. Understanding prion cell biology is fundamental for identifying potential drug targets for disease intervention. The development of permissive cell culture models has greatly enhanced our knowledge on entry, propagation and dissemination of TSE agents. However, despite extensive research, the precise mechanism of prion infection and potential strain effects remain enigmatic. This review summarizes our current knowledge of the cell biology and propagation of prions derived from cell culture experiments. We discuss recent findings on the trafficking of cellular and pathologic PrP, the potential sites of abnormal prion protein synthesis and potential co-factors involved in prion entry and propagation. PMID:23340381

  1. Molecular and cellular mechanisms of aortic stenosis.

    Science.gov (United States)

    Yetkin, Ertan; Waltenberger, Johannes

    2009-06-12

    Calcific aortic stenosis is the most common cause of aortic valve replacement in developed countries, and this condition increases in prevalence with advancing age. The fibrotic thickening and calcification are common eventual endpoint in both non-rheumatic calcific and rheumatic aortic stenoses. New observations in human aortic valves support the hypothesis that degenerative valvular aortic stenosis is the result of active bone formation in the aortic valve, which may be mediated through a process of osteoblast-like differentiation in these tissues. Additionally histopathologic evidence suggests that early lesions in aortic valves are not just a disease process secondary to aging, but an active cellular process that follows the classical "response to injury hypothesis" similar to the situation in atherosclerosis. Although there are similarities with the risk factor and as well as with the process of atherogenesis, not all the patients with coronary artery disease or atherosclerosis have calcific aortic stenosis. This review mainly focuses on the potential vascular and molecular mechanisms involved in the pathogenesis of aortic valve stenosis. Namely extracellular matrix remodeling, angiogenesis, inflammation, and eventually osteoblast-like differentiation resulting in bone formation have been shown to play a role in the pathogenesis of calcific aortic stenosis. Several mediators related to underlying mechanisms, including growth factors especially transforming growth factor-beta1 and vascular endothelial growth factors, angiogenesis, cathepsin enzymes, adhesion molecules, bone regulatory proteins and matrix metalloproteinases have been demonstrated, however the target to be attacked is not defined yet.

  2. Fish skin bacteria: Colonial and cellular hydrophobicity.

    Science.gov (United States)

    Sar, N; Rosenberg, E

    1987-05-01

    Bacteria were desorbed from the skin of healthy, fast-swimming fish by several procedures, including brief exposure to sonic oscillation and treatment with nontoxic surface active agents. The surface properties of these bacteria were studied by measuring their adhesion to hexadecane, as well as by a newly developed, simple method for studying the hydrophobicity of bacterial lawns. This method, referred to as the "Direction of Spreading" (DOS) method, consists of recording the direction to which a water drop spreads when introduced at the border between bacterial lawns and other surfaces. Of the 13 fish skin isolates examined, two strains were as hydrophobic as polystyrene by the DOS method. Suspended cells of one of these strains adhered strongly to hexadecane (84%), whereas cells of the other strain adhered poorly (13%). Another strain which was almost as hydrophobic as polystyrene by the DOS method did not adhere to hexadecane at all. Similarly, lawns of three other strains were more hydrophobic than glass by the DOS method, but cell suspensions prepared from these colonies showed little or no adhesion to hexadecane. The high colonial but relatively low cellular hydrophobicity could be due to a hydrophobic slime that is removed during the suspension and washing procedures. The possibility that specific bacteria assist in fish locomotion by changing the surface properties of the fish skin and by producing drag-reducing polymers is discussed.

  3. A hydrogen refill for cellular phone

    Science.gov (United States)

    Prosini, Pier Paolo; Gislon, Paola

    A device has been designed to generate hydrogen for a fuel cell powered cellular phone. The device is based on the chemical reaction between NaBH 4 and hydrochloric/water solution to satisfy the hydrogen request at room temperature and pressure. The operation mechanism and controlling method is based on the Kipp's gas generating apparatus. A prototype has been built and tested to evaluate the optimum salt/acid and acid/solution ratios and check the hydrogen mass flow rates upon operation and the pressure variation in stand-by condition. The system works delivering hydrogen flows ranging between 0 and 10 ml min -1. In a typical test the hydrogen flow was set to 5 ml min -1 to match a 1 W power fuel cell. The working pressure was slightly higher than the atmospheric one. The hydrogen capacity was as high as 2.5% (w/w). By converting this amount of hydrogen in electricity by a fuel cell working at 0.8 V it is possible to achieve a system energy density of about 720 Wh kg -1, four times larger than commercial high energy density lithium-ion batteries.

  4. Molecular processes in cellular arsenic metabolism

    International Nuclear Information System (INIS)

    Thomas, David J.

    2007-01-01

    Elucidating molecular processes that underlie accumulation, metabolism and binding of iAs and its methylated metabolites provides a basis for understanding the modes of action by which iAs acts as a toxin and a carcinogen. One approach to this problem is to construct a conceptual model that incorporates available information on molecular processes involved in the influx, metabolism, binding and efflux of arsenicals in cells. This conceptual model is initially conceived as a non-quantitative representation of critical molecular processes that can be used as a framework for experimental design and prediction. However, with refinement and incorporation of additional data, the conceptual model can be expressed in mathematical terms and should be useful for quantitative estimates of the kinetic and dynamic behavior of iAs and its methylated metabolites in cells. Development of a quantitative model will be facilitated by the availability of tools and techniques to manipulate molecular processes underlying transport of arsenicals across cell membranes or expression and activity of enzymes involved in methylation of arsenicals. This model of cellular metabolism might be integrated into more complex pharmacokinetic models for systemic metabolism of iAs and its methylated metabolites. It may also be useful in development of biologically based dose-response models describing the toxic and carcinogenic actions of arsenicals

  5. Modeling cellular effects of coal pollutants

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    The goal of this project is to develop and test models for the dose and dose-rate dependence of biological effects of coal pollutants on mammalian cells in tissue culture. Particular attention is given to the interaction of pollutants with the genetic material (deoxyribonucleic acid, or NDA) in the cell. Unlike radiation, which can interact directly with chromatin, chemical pollutants undergo numerous changes before the ultimate carcinogen becomes covalently bound to the DNA. Synthetic vesicles formed from a phospholipid bilayer are being used to investigate chemical transformations that may occur during the transport of pollutants across cellular membranes. The initial damage to DNA is rapidly modified by enzymatic repair systems in most living organisms. A model has been developed for predicting the effects of excision repair on the survival of human cells exposed to chemical carcinogens. In addition to the excision system, normal human cells also have tolerance mechanisms that permit continued growth and division of cells without removal of the damage. We are investigating the biological effect of damage passed to daughter cells by these tolerance mechanisms

  6. CELLULAR RESPONSES TO EGG-OIL (CHARISMON©

    Directory of Open Access Journals (Sweden)

    Jürgen Bereiter-Hahn

    2014-01-01

    Full Text Available Egg-oil (Charismon© is known for its beneficial action in wound healing and other skin irritancies and its antibacterial activity. The physiological basis for these actions has been investigated using cells in culture: HaCaT-cells (immortalized human keratinocytes, human endothelial cells in culture (HUVEC, peripheral blood mononuclear lymphocytes (PBML and a full thickness human skin model (FTSM. Emphasis was on the influence of egg-oil on cell migration and IL-8 production in HaCaT cells, respiration, mitochondrial membrane potential, reactive oxygen (ROS production and proliferation in HUVEC and HaCaT cells, cytokine and interleukin production in PBML and UV-light induced damage of FTSM. IL-8 production by HaCaT cells is stimulated by egg-oil whilst in phythemagglutinin-activated PBMLs production of the interleukins IL-2, IL-6, IL-10 and IFN-γ and TFN-α is reduced. ROS-production after H2O2 stimulation first is enhanced but later on reduced. Respiration becomes activated due to partial uncoupling of the mitochondrial respiratory chain and proliferation of HaCaT and HUVEC is reduced. Recovery of human epidermis cells in FTSM after UV-irradiation is strongly supported by egg-oil. These results support the view that egg-oil acts through reduction of inflammatory processes and ROS production. Both these processes are equally important in cellular aging as in healing of chronic wounds.

  7. Noise Reduction Potential of Cellular Metals

    Directory of Open Access Journals (Sweden)

    Björn Hinze

    2012-06-01

    Full Text Available Rising numbers of flights and aircrafts cause increasing aircraft noise, resulting in the development of various approaches to change this trend. One approach is the application of metallic liners in the hot gas path of aero-engines. At temperatures of up to 600 °C only metallic or ceramic structures can be used. Due to fatigue loading and the notch effect of the pores, mechanical properties of porous metals are superior to the ones of ceramic structures. Consequently, cellular metals like metallic foams, sintered metals, or sintered metal felts are most promising materials. However, acoustic absorption depends highly on pore morphology and porosity. Therefore, both parameters must be characterized precisely to analyze the correlation between morphology and noise reduction performance. The objective of this study is to analyze the relationship between pore morphology and acoustic absorption performance. The absorber materials are characterized using image processing based on two dimensional microscopy images. The sound absorption properties are measured using an impedance tube. Finally, the correlation of acoustic behavior, pore morphology, and porosity is outlined.

  8. Mobile telephony (cellular) and public health

    International Nuclear Information System (INIS)

    Saravi, F.D.

    2007-01-01

    One third of the world population uses mobile phones or cellular (TM), as possible repercussions on health has resulted in numerous studies. TM and their bases (antennae) exchange information through microwaves, which are non-ionizing electromagnetic radiations. Microwaves have thermal effects, which are avoided by current safety standards. However, there are lingering doubts about possible adverse health consequences of non-thermal effects of microwaves. As a whole, basic and epidemiological research on TM and cancer indicates a very low or nonexistent risk, although longer prospective studies are needed. In the nervous system, TM microwaves cause electrophysiological changes and modifications of blood flow, with little effect on performance. Possible effects on the thyroid gland, the reproductive system, and oxidative stress demand additional research. Some TM users complain of unspecific symptoms, but no causal relationship has been proved either in normal subjects or those self-characterized as hypersensitive to electromagnetic fields. Epidemiological research on populations living close to base stations suggests adverse effects from exposition, but experimental work has yielded contradictory results. The effects on children have just begun to be explored. TM may interfere with medical equipment when the phones are operated very close to the devices. Ironically, the clearest adverse effect of TM has no direct relationship with microwaves. The use of TM while driving causes a decrease in performance comparable to moderate consumption of alcohol and quadruples the risk of accidents. (author) [es

  9. Green Virtualization for Multiple Collaborative Cellular Operators

    KAUST Repository

    Farooq, Muhammad Junaid

    2017-06-05

    This paper proposes and investigates a green virtualization framework for infrastructure sharing among multiple cellular operators whose networks are powered by a combination of conventional and renewable sources of energy. Under the proposed framework, the virtual network formed by unifying radio access infrastructures of all operators is optimized for minimum energy consumption by deactivating base stations (BSs) with low traffic loads. The users initially associated to those BSs are off-loaded to neighboring active ones. A fairness criterion for collaboration based on roaming prices is introduced to cover the additional energy costs incurred by host operators. The framework also ensures that any collaborating operator is not negatively affected by its participation in the proposed virtualization. A multi-objective linear programming problem is formulated to achieve energy and cost efficiency of the networks\\' operation by identifying the set of inter-operator roaming prices. For the case when collaboration among all operators is infeasible due to profitability, capacity, or power constraints, an iterative algorithm is proposed to determine the groups of operators that can viably collaborate. Results show significant energy savings using the proposed virtualization as compared to the standalone case. Moreover, collaborative operators exploiting locally generated renewable energy are rewarded more than traditional ones.

  10. Cellular phones and risk of brain tumors.

    Science.gov (United States)

    Frumkin, H; Jacobson, A; Gansler, T; Thun, M J

    2001-01-01

    As cellular telephones are a relatively new technology, we do not yet have long-term follow-up on their possible biological effects. However, the lack of ionizing radiation and the low energy level emitted from cell phones and absorbed by human tissues make it unlikely that these devices cause cancer. Moreover, several well-designed epidemiologic studies find no consistent association between cell phone use and brain cancer. It is impossible to prove that any product or exposure is absolutely safe, especially in the absence of very long-term follow-up. Accordingly, the following summary from the Food and Drug Administration Center for Devices and Radiological Health offers advice to people concerned about their risk: If there is a risk from these products--and at this point we do not know that there is--it is probably very small. But if people are concerned about avoiding even potential risks, there are simple steps they can take to do so. People who must conduct extended conversations in their cars every day could switch to a type of mobile phone that places more distance between their bodies and the source of the RF, since the exposure level drops off dramatically with distance. For example, they could switch to: a mobile phone in which the antenna is located outside the vehicle, a hand-held phone with a built-in antenna connected to a different antenna mounted on the outside of the car or built into a separate package, or a headset with a remote antenna to a mobile phone carried at the waist. Again the scientific data do not demonstrate that mobile phones are harmful. But if people are concerned about the radiofrequency energy from these products, taking the simple precautions outlined above can reduce any possible risk. In addition, people who are concerned might choose digital rather than analog telephones, since the former use lower RF levels.

  11. Cysteinyl-Leukotriene Receptors and Cellular Signals

    Directory of Open Access Journals (Sweden)

    G. Enrico Rovati

    2007-01-01

    Full Text Available Cysteinyl-leukotrienes (cysteinyl-LTs exert a range of proinflammatory effects, such as constriction of airways and vascular smooth muscle, increase of endothelial cell permeability leading to plasma exudation and edema, and enhanced mucus secretion. They have proved to be important mediators in asthma, allergic rhinitis, and other inflammatory conditions, including cardiovascular diseases, cancer, atopic dermatitis, and urticaria. The classification into subtypes of the cysteinyl-LT receptors (CysLTRs was based initially on binding and functional data, obtained using the natural agonists and a wide range of antagonists. CysLTRs have proved remarkably resistant to cloning. However, in 1999 and 2000, the CysLT1R and CysLT2R were successfully cloned and both shown to be members of the G-protein coupled receptors (GPCRs superfamily. Molecular cloning has confirmed most of the previous pharmacological characterization and identified distinct expression patterns only partially overlapping. Recombinant CysLTRs couple to the Gq/11 pathway that modulates inositol phospholipids hydrolysis and calcium mobilization, whereas in native systems, they often activate a pertussis toxin-insensitive Gi/o-protein, or are coupled promiscuously to both G-proteins. Interestingly, recent data provide evidence for the existence of an additional receptor subtype that seems to respond to both cysteinyl-LTs and uracil nucleosides, and of an intracellular pool of CysLTRs that may have roles different from those of plasma membrane receptors. Finally, a cross-talk between the cysteinyl-LT and the purine systems is being delineated. This review will summarize recent data derived from studies on the molecular and cellular pharmacology of CysLTRs.

  12. Influence of income on tertiary students acquisition of cellular products

    Directory of Open Access Journals (Sweden)

    G. A.P Drotsky

    2007-12-01

    Full Text Available Purpose: The purpose of the article is to determine whether there are any differences between high and low-income group students in their selection of a cellular phone brand or network operator. Design/Methodology/Approach: Four hypotheses are set to determine if there are any significant differences between the two income groups in current decision-making. It is established that there exist no significant difference between high and low-income students in their selection of cellular phones and network operators. The levels of agreement or disagreement on various statements do, however, give an indication of the importance that students place on aspects that they view as important when acquiring a cellular phone or network operator. Findings: In the article, it is established that no significant differences exist between the two income groups. The levels of agreement or disagreement indicate the importance that subscription method, social value, service quality and branding has on student decision-making. Implications: The article provides a better understanding of the influence that income plays in student's decision-making in acquiring cellular products and services. Possible future research in student cellular usage can be guided through the information obtained in this article. Originality/Value: The article provides information to cellular network operators, service providers and cellular phone manufactures regarding the influence of income on students' acquisition of cellular products and services. Information from the article can assist in the establishment of marketing plans for the student market by these role players.

  13. Mechanisms and circumvention of cellular resistance to cisplatin.

    NARCIS (Netherlands)

    Hospers, Geesiena Alberdina Petronella

    1989-01-01

    Cisplatin (CDDP) is an active cytostatic agent. A limitation to its effectiveness initially or appearing during cystatic treatment is the occurrence of resistance. This thesis describes mechanisms wich are responsible for acquired cellular CDDP resistance. To investigate cellular CDDP resistance, a

  14. Is Glutathione the Major Cellular Target of Cisplatin?

    DEFF Research Database (Denmark)

    Kasherman, Yonit; Stürup, Stefan; gibson, dan

    2009-01-01

    Cisplatin is an anticancer drug whose efficacy is limited because tumors develop resistance to the drug. Resistant cells often have elevated levels of cellular glutathione (GSH), believed to be the major cellular target of cisplatin that inactivates the drug by binding to it irreversibly, forming...

  15. Analysis of Human Mobility Based on Cellular Data

    Science.gov (United States)

    Arifiansyah, F.; Saptawati, G. A. P.

    2017-01-01

    Nowadays not only adult but even teenager and children have then own mobile phones. This phenomena indicates that the mobile phone becomes an important part of everyday’s life. Based on these indication, the amount of cellular data also increased rapidly. Cellular data defined as the data that records communication among mobile phone users. Cellular data is easy to obtain because the telecommunications company had made a record of the data for the billing system of the company. Billing data keeps a log of the users cellular data usage each time. We can obtained information from the data about communication between users. Through data visualization process, an interesting pattern can be seen in the raw cellular data, so that users can obtain prior knowledge to perform data analysis. Cellular data processing can be done using data mining to find out human mobility patterns and on the existing data. In this paper, we use frequent pattern mining and finding association rules to observe the relation between attributes in cellular data and then visualize them. We used weka tools for finding the rules in stage of data mining. Generally, the utilization of cellular data can provide supporting information for the decision making process and become a data support to provide solutions and information needed by the decision makers.

  16. Cellular Automata Ideas in Digital Circuits and Switching Theory.

    Science.gov (United States)

    Siwak, Pawel P.

    1985-01-01

    Presents two examples which illustrate the usefulness of ideas from cellular automata. First, Lee's algorithm is recalled and its cellular nature shown. Then a problem from digraphs, which has arisen from analyzing predecessing configurations in the famous Conway's "game of life," is considered. (Author/JN)

  17. Quantum field theoretic behavior of a deterministic cellular automaton

    Energy Technology Data Exchange (ETDEWEB)

    Hooft, G ' t; Isler, K; Kalitzin, S [Inst. for Theoretical Physics, Utrecht (Netherlands)

    1992-11-16

    A certain class of cellular automata in 1 space +1 time dimension is shown to be closely related to quantum field theories containing Dirac fermions. In the massless case this relation can be studied analytically, while the introduction of Dirac mass requires numerical simulations. We show that in the last case the cellular automation describes the corresponding field theory only approximately. (orig.).

  18. Teen Perceptions of Cellular Phones as a Communication Tool

    Science.gov (United States)

    Jonas, Denise D.

    2011-01-01

    The excitement and interest in innovative technologies has spanned centuries. However, the invention of the cellular phone has surpassed previous technology interests, and changed the way we communicate today. Teens make up the fastest growing market of current cellular phone users. Consequently, the purpose of this study was to determine teen…

  19. Humoral and cellular immune responses to modified hepatitis B ...

    African Journals Online (AJOL)

    These findings indicate that the vaccine induced both a humoral and cellular ... Keywords: Hepatitis B virus, Plasmid DNA, Vaccine, Spleen cytokines, Humoral and cellular immune responses ... produced in mice. ... were performed and HBsAg specific IgM and IgG ..... and protection elicited against Plasmodium berghei.

  20. 47 CFR 22.911 - Cellular geographic service area.

    Science.gov (United States)

    2010-10-01

    ... Cellular Geographic Service Area (CGSA) of a cellular system is the geographic area considered by the FCC... application for modification of the CGSA using FCC Form 601, a depiction of what the carrier believes the CGSA... location and the locus of points where the predicted or measured median field strength finally drops to 32...

  1. Carica Papaya Seed Extract Enhances Cellular Response to Stress ...

    African Journals Online (AJOL)

    Therefore, the present study was carried out to investigate the role of Carica papaya seed (CPS) extract that contains, Benzyl Isothiocyanates, one of the inducers of phase II enzymes in the regulation of cellular stress. The cellular responses were observed in U937 cells (human monocyte/macrophage cell line) at the ...

  2. Analysis of Drop Call Probability in Well Established Cellular ...

    African Journals Online (AJOL)

    Technology in Africa has increased over the past decade. The increase in modern cellular networks requires stringent quality of service (QoS). Drop call probability is one of the most important indices of QoS evaluation in a large scale well-established cellular network. In this work we started from an accurate statistical ...

  3. Cellular Phone Text Communication in English Language Among ...

    African Journals Online (AJOL)

    Considering the place of English in Nigeria, pupils and students are enjoined to use it constantly in their activities including phone calls. In view of the significant roles that cellular phones play in the lives of youths, and sustainable development of the economy, this paper looks into Nigerian youths' cellular phone text ...

  4. Optimizing Cellular Networks Enabled with Renewal Energy via Strategic Learning.

    Science.gov (United States)

    Sohn, Insoo; Liu, Huaping; Ansari, Nirwan

    2015-01-01

    An important issue in the cellular industry is the rising energy cost and carbon footprint due to the rapid expansion of the cellular infrastructure. Greening cellular networks has thus attracted attention. Among the promising green cellular network techniques, the renewable energy-powered cellular network has drawn increasing attention as a critical element towards reducing carbon emissions due to massive energy consumption in the base stations deployed in cellular networks. Game theory is a branch of mathematics that is used to evaluate and optimize systems with multiple players with conflicting objectives and has been successfully used to solve various problems in cellular networks. In this paper, we model the green energy utilization and power consumption optimization problem of a green cellular network as a pilot power selection strategic game and propose a novel distributed algorithm based on a strategic learning method. The simulation results indicate that the proposed algorithm achieves correlated equilibrium of the pilot power selection game, resulting in optimum green energy utilization and power consumption reduction.

  5. Basic Ideas to Approach Metastability in Probabilistic Cellular Automata

    NARCIS (Netherlands)

    Cirillo, Emilio N. M.; Nardi, Francesca R.; Spitoni, Cristian

    2016-01-01

    Cellular Automata are discrete--time dynamical systems on a spatially extended discrete space which provide paradigmatic examples of nonlinear phenomena. Their stochastic generalizations, i.e., Probabilistic Cellular Automata, are discrete time Markov chains on lattice with finite single--cell

  6. Cellular Chaperones As Therapeutic Targets in ALS to Restore Protein Homeostasis and Improve Cellular Function

    Directory of Open Access Journals (Sweden)

    Bernadett Kalmar

    2017-09-01

    Full Text Available Heat shock proteins (Hsps are ubiquitously expressed chaperone proteins that enable cells to cope with environmental stresses that cause misfolding and denaturation of proteins. With aging this protein quality control machinery becomes less effective, reducing the ability of cells to cope with damaging environmental stresses and disease-causing mutations. In neurodegenerative disorders such as Amyotrophic Lateral Sclerosis (ALS, such mutations are known to result in protein misfolding, which in turn results in the formation of intracellular aggregates cellular dysfunction and eventual neuronal death. The exact cellular pathology of ALS and other neurodegenerative diseases has been elusive and thus, hindering the development of effective therapies. However, a common scheme has emerged across these “protein misfolding” disorders, in that the mechanism of disease involves one or more aspects of proteostasis; from DNA transcription, RNA translation, to protein folding, transport and degradation via proteosomal and autophagic pathways. Interestingly, members of the Hsp family are involved in each of these steps facilitating normal protein folding, regulating the rate of protein synthesis and degradation. In this short review we summarize the evidence that suggests that ALS is a disease of protein dyshomeostasis in which Hsps may play a key role. Overwhelming evidence now indicates that enabling protein homeostasis to cope with disease-causing mutations might be a successful therapeutic strategy in ALS, as well as other neurodegenerative diseases. Novel small molecule co-inducers of Hsps appear to be able to achieve this aim. Arimoclomol, a hydroxylamine derivative, has shown promising results in cellular and animal models of ALS, as well as other protein misfolding diseases such as Inclusion Body Myositis (IBM. Initial clinical investigations of Arimoclomol have shown promising results. Therefore, it is possible that the long series of

  7. Behaviour of cellular structures with fluid fillers under impact loading

    Directory of Open Access Journals (Sweden)

    Matej Vesenjak

    2007-03-01

    Full Text Available The paper investigates the behaviour of closed- and open-cell cellular structures under uniaxial impact loading by means of computational simulations using the explicit nonlinear finite element code LS-DYNA. Simulations also consider the influence of pore fillers and the base material strain rate sensitivity. The behaviour of closed-cell cellular structure has been evaluated with use of the representative volume element, where the influence of residual gas inside the closed pores has been studied. Open- cell cellular structure was modelled as a whole to properly account for considered fluid flow through the cells, which significantly influences macroscopic behaviour of the cellular structure. The fluid has been modelled by applying a meshless Smoothed Particle Hydrodynamics (SPH method. Parametric computational simulations provide grounds for optimization of cellular structures to satisfy different requirements, which makes them very attractive for use in general engineering applications.

  8. Application of Digital Cellular Radio for Mobile Location Estimation

    Directory of Open Access Journals (Sweden)

    Farhat Anwar

    2012-08-01

    Full Text Available The capability to locate the position of mobiles is a prerequisite to implement a wide range of evolving ITS services. Radiolocation has the potential to serve a wide geographical area. This paper reports an investigation regarding the feasibility of utilizing cellular radio for the purpose of mobile location estimation. Basic strategies to be utilized for location estimation are elaborated. Two possible approaches for cellular based location estimation are investigated with the help of computer simulation. Their effectiveness and relative merits and demerits are identified. An algorithm specifically adapted for cellular environment is reported with specific features where mobiles, irrespective of their numbers, can locate their position without adversely loading the cellular system.Key Words: ITS, GSM, Cellular Radio, DRGS, GPS.

  9. Cellular phones were found to pose no health risks

    International Nuclear Information System (INIS)

    Puranen, L.

    1997-01-01

    A cellular phone emits radiation very close to a person's head. Any harmful effects that might arise from the use of cellular phones are being studied carefully, but so far no health risks have been determined. However, the phones may interfere with the operation of electrical devices located close-by, such as a cardiac pacemaker. The biological effects of the microwaves emitted by cellular phones might be based on the resultant higher temperatures in the tissues of the head. Since, even in the worst cases, a cellular phone cannot raise the temperature of tissues by more than some tenths of a degree, no health risks based on thermal effects can be attributed to the use of a cellular phone. No reliable theory has been presented for the non-thermal effects of microwaves. Such effects may exist, however. The studies conducted so far have been unable to show that these effects might be harmful to human health. (orig.)

  10. Numerical Study on Critical Wedge Angle of Cellular Detonation Reflections

    International Nuclear Information System (INIS)

    Gang, Wang; Kai-Xin, Liu; De-Liang, Zhang

    2010-01-01

    The critical wedge angle (CWA) for the transition from regular reflection (RR) to Mach reflection (MR) of a cellular detonation wave is studied numerically by an improved space-time conservation element and solution element method together with a two-step chemical reaction model. The accuracy of that numerical way is verified by simulating cellular detonation reflections at a 19.3° wedge. The planar and cellular detonation reflections over 45°–55° wedges are also simulated. When the cellular detonation wave is over a 50° wedge, numerical results show a new phenomenon that RR and MR occur alternately. The transition process between RR and MR is investigated with the local pressure contours. Numerical analysis shows that the cellular structure is the essential reason for the new phenomenon and the CWA of detonation reflection is not a certain angle but an angle range. (fundamental areas of phenomenology(including applications))

  11. Observations of cellular transformation products in nickel-base superalloys

    International Nuclear Information System (INIS)

    Barlow, C.Y.; Ralph, B.

    1979-01-01

    Transmission electron microscopy has been used to identify the products in cellularly transformed regions of alloys based on the Nimonic 80 A composition. The commercial alloy is shown to undergo a small degree of cellular transformation even after conventional heat treatments, while recrystallization is found to increase the incidence of this reaction type. Low carbon versions of this alloy demonstrate cellular precipitation over a wider range of heat treatments. It is shown that the cellular reaction may take place in these alloys under a variety of different conditions and with a range of driving forces. Reasons for this unexpected behaviour are offeredm as is a suggestion as to why the cellular reaction occurs on a local scale. (author)

  12. Cellular Senescence in Postmitotic Cells: Beyond Growth Arrest.

    Science.gov (United States)

    Sapieha, Przemyslaw; Mallette, Frédérick A

    2018-04-25

    In mitotic cells, cellular senescence is a permanent state of G1 arrest, that may have evolved in parallel to apoptosis, to limit proliferation of damaged cells and oncogenesis. Recent studies have suggested that postmitotic cells are also capable of entering a state of senescence, although the repercussions of postmitotic cellular senescence (PoMiCS) on tissue health and function are currently ill-defined. In tissues made largely of post-mitotic cells, it is evolutionary advantageous to preserve cellular integrity and cellular senescence of post-mitotic cells may prevent stressor-induced tissue degeneration and promote tissue repair. Paradoxically, PoMiCS may also contribute to disease progression through the generation of inflammatory mediators, termed the senescence-associated secretory phenotype. Here, we discuss the potential roles of PoMiCS and propose to enlarge the current definition of cellular senescence to postmitotic terminally differentiated cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Joint User Scheduling and MU-MIMO Hybrid Beamforming Algorithm for mmWave FDMA Massive MIMO System

    Directory of Open Access Journals (Sweden)

    Jing Jiang

    2016-01-01

    Full Text Available The large bandwidth and multipath in millimeter wave (mmWave cellular system assure the existence of frequency selective channels; it is necessary that mmWave system remains with frequency division multiple access (FDMA and user scheduling. But for the hybrid beamforming system, the analog beamforming is implemented by the same phase shifts in the entire frequency band, and the wideband phase shifts may not be harmonious with all users scheduled in frequency resources. This paper proposes a joint user scheduling and multiuser hybrid beamforming algorithm for downlink massive multiple input multiple output (MIMO orthogonal frequency division multiple access (OFDMA systems. In the first step of user scheduling, the users with identical optimal beams form an OFDMA user group and multiplex the entire frequency resource. Then base station (BS allocates the frequency resources for each member of OFDMA user group. An OFDMA user group can be regarded as a virtual user; thus it can support arbitrary MU-MIMO user selection and beamforming algorithms. Further, the analog beamforming vectors employ the best beam of each selected MU-MIMO user and the digital beamforming algorithm is solved by weight MMSE to acquire the best performance gain and mitigate the interuser inference. Simulation results show that hybrid beamforming together with user scheduling can greatly improve the performance of mmWave OFDMA massive MU-MIMO system.

  14. The Relationship between Cellular Phone Use, Performance, and Reaction Time among College Students: Implications for Cellular Phone Use while Driving

    Science.gov (United States)

    Szyfman, Adam; Wanner, Gregory; Spencer, Leslie

    2003-01-01

    Two studies were performed to determine the relationship between cellular phone use and either reaction time or performance among college students. In the first study 60 undergraduates completed a computerized reaction time test. Mean reaction times were significantly higher when participants were talking on a cellular phone, either handheld or on…

  15. Reduced labor and condensed schedules with cellular concrete solutions

    Energy Technology Data Exchange (ETDEWEB)

    Lavis, D. [CEMATRIX Inc., Calgary, AB (Canada)

    2008-07-01

    This paper discussed the use of cellular concrete materials in oil sands tank base foundation systems, shallow buried utility insulation systems, roadways, slabs, and buried modules. The concrete is formed from Portland cement, water, specialized pre-formed foaming agents, and air mixed in controlled proportions. Fly ash and polypropylene or glass fibers can also be used as additions. Cellular concrete can often be used to speed up construction and minimize labour requirements. Cellular concrete can be cast-in-place, and has soil-stabilizing and self-compacting features. The concrete can be produced and placed on-site at rates exceeding 120 cubic meters per hour. Cellular concrete can be pumped into place over long distances through flexible hoses. A case study comparing the cellular concrete to traditional plastic foam insulation was used to demonstrate the equivalency and adequacy of insulation, structural properties and installation costs. The study showed that although the cellular concrete had a high installation cost, greater compressive strength was gained. The concrete was self-levelling and did not require compaction or vibration. The use of the cellular concrete resulted in an accelerated construction schedule. 6 refs., 2 tabs., 6 figs.

  16. The Effects Radiation on Cellular Components of the Immune

    International Nuclear Information System (INIS)

    Zubaidah-Alatas

    2001-01-01

    The immune system describes the body's ability to defend itself against various foreign intruders named as antigens by calling on an immune mechanism. Antigens penetration into body activate the body's immune system that may be humoral response, cellular response, or both. The immune response is primarily mediated by two cell types, lymphocyte and macrophage. This paper will discuss the cellular component of immune system and the radiation effects on various cells involved in system. Moreover, the effects of radiation on humoral and cellular responses and the relation among immunity, cancer and radiotherapy are also described. (author)

  17. Human cellular restriction factors that target HIV-1 replication

    Directory of Open Access Journals (Sweden)

    Jeang Kuan-Teh

    2009-09-01

    Full Text Available Abstract Recent findings have highlighted roles played by innate cellular factors in restricting intracellular viral replication. In this review, we discuss in brief the activities of apolipoprotein B mRNA-editing enzyme 3G (APOBEC3G, bone marrow stromal cell antigen 2 (BST-2, cyclophilin A, tripartite motif protein 5 alpha (Trim5α, and cellular microRNAs as examples of host restriction factors that target HIV-1. We point to countermeasures encoded by HIV-1 for moderating the potency of these cellular restriction functions.

  18. The first case of synchronous cellular angiofibromas of the scrotum

    Directory of Open Access Journals (Sweden)

    Chih-Chen Hsu

    2016-06-01

    Full Text Available Cellular angiofibroma is a rare benign tumor which is found in the vulvovaginal or inguinoscrotal region. To the best of our knowledge, there have been no reports that describe two cellular angiofibromas on the same side of the scrotum. Here, we report the case of an 89-year-old male patient with two scrotal tumors which were proven to be cellular angiofibromas after the biopsy specimen was examined. The tumor markers were CD34 (+, focally positive for S-100, actin (−, desmin (−, estrogen receptor (−, progesterone receptor (−, beta-catenin (−, CD99 (−, and B-cell lymphoma 2 (−.

  19. Cellular Angiofibroma of Oral Mucosa: Report of Two Cases

    Science.gov (United States)

    2009-01-01

    Cellular angiofibroma is a benign vascular neoplasm that typically arises in the vulva, perineal, and paratesticular region. Microscopically the lesions exhibit multiple small, non-dilated capillary channels, many of which contain erythrocytes. The endothelial lining cells are prominent, with monomorphic oval nuclei. Interposed among the vessels are both delicate and mature collagen fibers with fibroblastic hypercellularity that is variable in older lesions where sclerosis is prominent. The lesions usually do not recur following simple excision. Recent evidence indicates that cellular angiofibromas may be cytogenetically related to spindle cell lipoma. This represents the first reported instances of cellular angiofibroma in the oral cavity. PMID:19644547

  20. Extended Cellular Automata Models of Particles and Space-Time

    Science.gov (United States)

    Beedle, Michael

    2005-04-01

    Models of particles and space-time are explored through simulations and theoretical models that use Extended Cellular Automata models. The expanded Cellular Automata Models consist go beyond simple scalar binary cell-fields, into discrete multi-level group representations like S0(2), SU(2), SU(3), SPIN(3,1). The propagation and evolution of these expanded cellular automatas are then compared to quantum field theories based on the "harmonic paradigm" i.e. built by an infinite number of harmonic oscillators, and with gravitational models.

  1. Path searching in switching networks using cellular algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Koczy, L T; Langer, J; Legendi, T

    1981-01-01

    After a survey of the important statements in the paper A Mathematical Model of Path Searching in General Type Switching Networks (see IBID., vol.25, no.1, p.31-43, 1981) the authors consider the possible implementation for cellular automata of the algorithm introduced there. The cellular field used consists of 5 neighbour 8 state cells. Running times required by a traditional serial processor and by the cellular field, respectively, are compared. By parallel processing this running time can be reduced. 5 references.

  2. Elastomeric Cellular Structure Enhanced by Compressible Liquid Filler

    Science.gov (United States)

    Sun, Yueting; Xu, Xiaoqing; Xu, Chengliang; Qiao, Yu; Li, Yibing

    2016-05-01

    Elastomeric cellular structures provide a promising solution for energy absorption. Their flexible and resilient nature is particularly relevant to protection of human bodies. Herein we develop an elastomeric cellular structure filled with nanoporous material functionalized (NMF) liquid. Due to the nanoscale infiltration in NMF liquid and its interaction with cell walls, the cellular structure has a much enhanced mechanical performance, in terms of loading capacity and energy absorption density. Moreover, it is validated that the structure is highly compressible and self-restoring. Its hyper-viscoelastic characteristics are elucidated.

  3. Manufacturing processes of cellular metals. Part I. Liquid route processes

    International Nuclear Information System (INIS)

    Fernandez, P.; Cruz, L. J.; Coleto, J.

    2008-01-01

    With its interesting and particular characteristics, cellular metals are taking part of the great family of new materials. They can have open or closed porosity. At the present time, the major challenge for the materials researchers is based in the manufacturing techniques improvement in order to obtain reproducible and reliable cellular metals with quality. In the present paper, the different production methods to manufacture cellular metals by liquid route are reviewed; making a short description about the main parameters involved and the advantages and drawbacks in each of them. (Author) 106 refs

  4. Study of Electromagnetic Fields on Cellular Systems Study of Electromagnetic Fields on Cellular Systems

    Directory of Open Access Journals (Sweden)

    Sergio Solorio-Meza

    2012-02-01

    Full Text Available Durante las últimas décadas, el interés por explicar el efecto de la radiación no ionizante, como es el caso de los campos electromagnéticos (CEM sobre sistemas celulares ha aumentado considerablemente. En este artículo se describe la interacción que existe entre los CEM y sistemas biológicos. Se discute el efecto de la estimulación electromagnética a diferentes frecuencias e intensidades en cultivos celulares. Resultados preliminares al estimular células de neuroblastomas SK-NSH con campos electromagnéticos de extra baja frecuencia (CEM-EBF, CEM que van del rango de 3 a 30 Hz, indican que se induce un estrés celularque se refleja en variaciones en la expresión de proteínas respecto al grupo de células no estimuladas. En particular, la expresión de las proteínas muestra que los CEM-EBF producen cambios en las proteínas presentes en condiciones normales o basales en las células, es decir, aparecen nuevas proteínas o existe un aumento en la cantidad de ellas.In the last decades the interest to study the effect of non-ionizing radiation, such as the electromagnetic fields (EMF on cellular systems has increased. In this article the interaction between EMF and biological systems is described. An analysis of the effect of the electromagnetic stimulation at different frequencies and intensities on cell cultures is performed. Preliminary results show that the stimulation with extremely low frequency electromagnetic fields (ELF-EMF, EMF from 3 to 30 Hz, on the cellular line of neuroblastomaSK-NSH induces cellular stress. This is reflected by a variation in the proteins expression in comparison with the group of cells no stimulated. In particular, the proteins expression shows that the ELF-EMF produce changes in the current proteins in normal or basal conditionsin the cells, that is, new proteins appear or there is evidence of an increasing in theamount of them.

  5. 47 CFR 90.672 - Unacceptable interference to non-cellular 800 MHz licensees from 800 MHz cellular systems or part...

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Unacceptable interference to non-cellular 800 MHz licensees from 800 MHz cellular systems or part 22 Cellular Radiotelephone systems, and within the... Procedures and Process-Unacceptable Interference § 90.672 Unacceptable interference to non-cellular 800 MHz...

  6. Cellular potts models multiscale extensions and biological applications

    CERN Document Server

    Scianna, Marco

    2013-01-01

    A flexible, cell-level, and lattice-based technique, the cellular Potts model accurately describes the phenomenological mechanisms involved in many biological processes. Cellular Potts Models: Multiscale Extensions and Biological Applications gives an interdisciplinary, accessible treatment of these models, from the original methodologies to the latest developments. The book first explains the biophysical bases, main merits, and limitations of the cellular Potts model. It then proposes several innovative extensions, focusing on ways to integrate and interface the basic cellular Potts model at the mesoscopic scale with approaches that accurately model microscopic dynamics. These extensions are designed to create a nested and hybrid environment, where the evolution of a biological system is realistically driven by the constant interplay and flux of information between the different levels of description. Through several biological examples, the authors demonstrate a qualitative and quantitative agreement with t...

  7. Taming the sphinx: Mechanisms of cellular sphingolipid homeostasis.

    Science.gov (United States)

    Olson, D K; Fröhlich, F; Farese, R V; Walther, T C

    2016-08-01

    Sphingolipids are important structural membrane components of eukaryotic cells, and potent signaling molecules. As such, their levels must be maintained to optimize cellular functions in different cellular membranes. Here, we review the current knowledge of homeostatic sphingolipid regulation. We describe recent studies in Saccharomyces cerevisiae that have provided insights into how cells sense changes in sphingolipid levels in the plasma membrane and acutely regulate sphingolipid biosynthesis by altering signaling pathways. We also discuss how cellular trafficking has emerged as an important determinant of sphingolipid homeostasis. Finally, we highlight areas where work is still needed to elucidate the mechanisms of sphingolipid regulation and the physiological functions of such regulatory networks, especially in mammalian cells. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon. Copyright © 2015. Published by Elsevier B.V.

  8. Full-Duplex Communications in Large-Scale Cellular Networks

    KAUST Repository

    Alammouri, Ahmad

    2016-01-01

    /downlink interference. This thesis presents a tractable framework, based on stochastic geometry, to study FD communications in multi-tier cellular networks. Particularly, we assess the FD communications effect on the network performance and quantify the associated gains

  9. Modeling and Analysis of Cellular CDMA Forward Channel

    National Research Council Canada - National Science Library

    Tighe, Jan

    2001-01-01

    In this thesis, we develop the forward channel model for a DS-CDMA cellular system operating in a slow-flat Rayleigh fading and log normal shadowing environment, which incorporates the extended Hata...

  10. Consumer-purchasing Motives in Nigerian Cellular Phone Market ...

    African Journals Online (AJOL)

    Consumer-purchasing Motives in Nigerian Cellular Phone Market: An Empirical Investigation. ... Nigerian consumers to identify their motives for purchasing new mobile phones on one hand, and factors affecting operator choice on the other.

  11. Correlation between membrane fluidity cellular development and stem cell differentiation

    KAUST Repository

    Noutsi, Bakiza Kamal

    2016-01-01

    Cell membranes are made up of a complex structure of lipids and proteins that diffuse laterally giving rise to what we call membrane fluidity. During cellular development, such as neuronal differentiation, cell membranes undergo dramatic structural

  12. Cellular immobilization within microfluidic microenvironments: dielectrophoresis with polyelectrolyte multilayers.

    Science.gov (United States)

    Forry, Samuel P; Reyes, Darwin R; Gaitan, Michael; Locascio, Laurie E

    2006-10-25

    The development of biomimetic microenvironments will improve cell culture techniques by enabling in vitro cell cultures that mimic in vivo behavior; however, experimental control over attachment, cellular position, or intercellular distances within such microenvironments remains challenging. We report here the rapid and controllable immobilization of suspended mammalian cells within microfabricated environments using a combination of electronic (dielectrophoresis, DEP) and chemical (polyelectrolyte multilayers, PEMS) forces. While cellular position within the microsystem is rapidly patterned via intermittent DEP trapping, persistent adhesion after removal of electronic forces is enabled by surface treatment with PEMS that are amenable to cellular attachment. In contrast to DEP trapping alone, persistent adhesion enables the soluble microenvironment to be systematically varied, facilitating the use of soluble probes of cell state and enabling cellular characterization in response to various soluble stimuli.

  13. Matrix remodeling between cells and cellular interactions with collagen bundle

    Science.gov (United States)

    Kim, Jihan; Sun, Bo

    When cells are surrounded by complex environment, they continuously probe and interact with it by applying cellular traction forces. As cells apply traction forces, they can sense rigidity of their local environment and remodel the matrix microstructure simultaneously. Previous study shows that single human carcinoma cell (MDA-MB-231) remodeled its surrounding extracellular matrix (ECM) and the matrix remodeling was reversible. In this study we examined the matrix microstructure between cells and cellular interaction between them using quantitative confocal microscopy. The result shows that the matrix microstructure is the most significantly remodeled between cells consisting of aligned, and densified collagen fibers (collagen bundle)., the result shows that collagen bundle is irreversible and significantly change micromechanics of ECM around the bundle. We further examined cellular interaction with collagen bundle by analyzing dynamics of actin and talin formation along with the direction of bundle. Lastly, we analyzed dynamics of cellular protrusion and migrating direction of cells along the bundle.

  14. Cellular metabolism regulates contact sites between vacuoles and mitochondria

    NARCIS (Netherlands)

    Hönscher, Carina; Mari, Muriel; Auffarth, Kathrin; Bohnert, Maria; Griffith, Janice; Geerts, Willie; van der Laan, Martin; Cabrera, Margarita; Reggiori, Fulvio; Ungermann, Christian

    2014-01-01

    Emerging evidence suggests that contact sites between different organelles form central hubs in the coordination of cellular physiology. Although recent work has emphasized the crucial role of the endoplasmic reticulum in interorganellar crosstalk, the cooperative behavior of other organelles is

  15. A generalized cellular automata approach to modeling first order ...

    Indian Academy of Sciences (India)

    ... inhibitors deforming the allosteric site or inhibitors changing the structure of active ... Cell-based models with discrete state variables, such as Cellular Automata ... capture the essential features of a discrete real system, consisting of space, ...

  16. Symposium on molecular and cellular mechanisms of mutagenesis

    International Nuclear Information System (INIS)

    1981-01-01

    These proceedings contain abstracts only of the 21 papers presented at the Sympsoium. The papers dealt with molecular mechanisms of mutagenesis and cellular responses to chemical and physical mutagenic agents

  17. Cellular Senescence Promotes Adverse Effects of Chemotherapy and Cancer Relapse

    NARCIS (Netherlands)

    Demaria, Marco; O'Leary, Monique N.; Chang, Jianhui; Shao, Lijian; Liu, Su; Alimirah, Fatouma; Koenig, Kristin; Le, Catherine; Mitin, Natalia; Deal, Allison M.; Alston, Shani; Academia, Emmeline C.; Kilmarx, Sumner; Valdovinos, Alexis; Wang, Boshi; de Bruin, Alain; Kennedy, Brian K.; Melov, Simon; Zhou, Daohong; Sharpless, Norman E.; Muss, Hyman; Campisi, Judith

    Cellular senescence suppresses cancer by irreversibly arresting cell proliferation. Senescent cells acquire a proinfl ammatory senescence-associated secretory phenotype. Many genotoxic chemotherapies target proliferating cells nonspecifi cally, often with adverse reactions. In accord with prior

  18. Virtualized cognitive network architecture for 5G cellular networks

    KAUST Repository

    Elsawy, Hesham; Dahrouj, Hayssam; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2015-01-01

    , tactile Internet, online gaming, multimedia). Such an ossified architecture imposes several hurdles against achieving the ambitious metrics of next generation cellular systems. This article first highlights the features and drawbacks of such architectural

  19. Energy Sharing Framework for Microgrid-Powered Cellular Base Stations

    KAUST Repository

    Farooq, Muhammad Junaid; Ghazzai, Hakim; Kadri, Abdullah; Elsawy, Hesham; Alouini, Mohamed-Slim

    2017-01-01

    Cellular base stations (BSs) are increasingly becoming equipped with renewable energy generators to reduce operational expenditures and carbon footprint of wireless communications. Moreover, advancements in the traditional electricity grid allow two

  20. Cellular Plasticity of Epithelial Cells-Cause of Metastasis

    National Research Council Canada - National Science Library

    Sukumar, Saraswati

    2005-01-01

    .... We present a novel concept that cancer epithelial cells, possibly of stem cell origin, have inherent cellular plasticity and can differentiate into endothelial cells and form microvessels that serve...

  1. Symposium on molecular and cellular mechanisms of mutagenesis

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    These proceedings contain abstracts only of the 21 papers presented at the Sympsoium. The papers dealt with molecular mechanisms of mutagenesis and cellular responses to chemical and physical mutagenic agents. (ERB)

  2. Influence of corona charging in cellular polyethylene film

    International Nuclear Information System (INIS)

    Ortega Brana, Gustavo; Magraner, Francisco; Quijano, Alfredo; Llovera Segovia, Pedro

    2011-01-01

    Cellular polymers have recently attracted attention for their property of exhibiting a piezoelectric constant when they are electrically charged. The electrostatic charge generated in the voids by the internal discharges creates and internal macrodipole which is responsible for the piezoelectric effect. Charging by corona discharge is the most used method for cellular polymers. Many works has been published on polypropylene and polyethylene films mainly focused on the required expansion process or on the results obtained for raw cellular materials electrically activated. Our work is based on commercial polyethylene cellular films which have been physically characterized and electrically activated. The effect of thermal treatment, physical uniaxial or biaxial stretching and corona charging was investigated. The new method of corona charging improved the piezoelectric constant under other activation conditions.

  3. Electromagnetic Radiation Exposure from Cellular Base Station: A ...

    African Journals Online (AJOL)

    Electromagnetic Radiation Exposure from Cellular Base Station: A Concern for Public ... as well as safety guidelines relating to exposure of non-ionizing radiation. Global System for Mobile Communication (GSM) operators claimed that their ...

  4. Influence of corona charging in cellular polyethylene film

    Energy Technology Data Exchange (ETDEWEB)

    Ortega Brana, Gustavo; Magraner, Francisco; Quijano, Alfredo [Instituto Tecnologico de la Energia (ITE), Av. Juan de la Cierva 24, Parque Tecnologico de Valencia, 46980 Paterna-Valencia (Spain); Llovera Segovia, Pedro, E-mail: gustavo.ortega@ite.es [Instituto de TecnologIa Electrica - Universitat Politecnica de Valencia, Camino de Vera s/n 46022-Valencia (Spain)

    2011-06-23

    Cellular polymers have recently attracted attention for their property of exhibiting a piezoelectric constant when they are electrically charged. The electrostatic charge generated in the voids by the internal discharges creates and internal macrodipole which is responsible for the piezoelectric effect. Charging by corona discharge is the most used method for cellular polymers. Many works has been published on polypropylene and polyethylene films mainly focused on the required expansion process or on the results obtained for raw cellular materials electrically activated. Our work is based on commercial polyethylene cellular films which have been physically characterized and electrically activated. The effect of thermal treatment, physical uniaxial or biaxial stretching and corona charging was investigated. The new method of corona charging improved the piezoelectric constant under other activation conditions.

  5. Quantifying the global cellular thiol-disulfide status

    DEFF Research Database (Denmark)

    Hansen, Rosa E; Roth, Doris; Winther, Jakob R

    2009-01-01

    It is widely accepted that the redox status of protein thiols is of central importance to protein structure and folding and that glutathione is an important low-molecular-mass redox regulator. However, the total cellular pools of thiols and disulfides and their relative abundance have never been...... determined. In this study, we have assembled a global picture of the cellular thiol-disulfide status in cultured mammalian cells. We have quantified the absolute levels of protein thiols, protein disulfides, and glutathionylated protein (PSSG) in all cellular protein, including membrane proteins. These data...... cell types. However, when cells are exposed to a sublethal dose of the thiol-specific oxidant diamide, PSSG levels increase to >15% of all protein cysteine. Glutathione is typically characterized as the "cellular redox buffer"; nevertheless, our data show that protein thiols represent a larger active...

  6. Cellular Clocks : Coupled Circadian Dispatch and Cell Division Cycles

    NARCIS (Netherlands)

    Merrow, Martha; Roenneberg, Till

    2004-01-01

    Gating of cell division by the circadian clock is well known, yet its mechanism is little understood. Genetically tractable model systems have led to new hypotheses and questions concerning the coupling of these two cellular cycles.

  7. An Optically-Assisted 3-D Cellular Array Machine

    National Research Council Canada - National Science Library

    Lin, Freddie

    1997-01-01

    .... In this Phase II project, we developed a discrete-component based Cellular Neural Network (CNN) circuitry, which can perform CNN based analog image processing, such as edge detection and image enhancement, in real time...

  8. Production, properties, and applications of hydrocolloid cellular solids.

    Science.gov (United States)

    Nussinovitch, Amos

    2005-02-01

    Many common synthetic and edible materials are, in fact, cellular solids. When classifying the structure of cellular solids, a few variables, such as open vs. closed cells, flexible vs. brittle cell walls, cell-size distribution, cell-wall thickness, cell shape, the uniformity of the structure of the cellular solid and the different scales of length are taken into account. Compressive stress-strain relationships of most cellular solids can be easily identified according to their characteristic sigmoid shape, reflecting three deformation mechanisms: (i) elastic distortion under small strains, (ii) collapse and/or fracture of the cell walls, and (iii) densification. Various techniques are used to produce hydrocolloid (gum) cellular solids. The products of these include (i) sponges, obtained when the drying gel contains the occasionally produced gas bubbles; (ii) sponges produced by the immobilization of microorganisms; (iii) solid foams produced by drying foamed solutions or gels containing oils, and (iv) hydrocolloid sponges produced by enzymatic reactions. The porosity of the manufactured cellular solid is subject to change and depends on its composition and the processing technique. The porosity is controlled by a range of methods and the resulting surface structures can be investigated by microscopy and analyzed using fractal methods. Models used to describe stress-strain behaviors of hydrocolloid cellular solids as well as multilayered products and composites are discussed in detail in this manuscript. Hydrocolloid cellular solids have numerous purposes, simple and complex, ranging from dried texturized fruits to carriers of vitamins and other essential micronutrients. They can also be used to control the acoustic response of specific dry food products, and have a great potential for future use in countless different fields, from novel foods and packaging to medicine and medical care, daily commodities, farming and agriculture, and the environmental, chemical

  9. DURIP: Mitigating Attacks on Mobile Devices and Critical Cellular Infrastructure

    Science.gov (United States)

    2016-03-03

    services. From mobile banking and location- based services to the real-time streaming of music and video, cellular networks now provide advanced voice...time streaming of music and video, cellular networks now provide advanced voice and data services to more than 4.5 billion subscribers around the world...will receive scholarships or fellowships for further studies in science , mathematics, engineering or technology fields: Student Metrics This section

  10. Hydrogen peroxide probes directed to different cellular compartments.

    OpenAIRE

    Mikalai Malinouski; You Zhou; Vsevolod V Belousov; Dolph L Hatfield; Vadim N Gladyshev

    2011-01-01

    Background Controlled generation and removal of hydrogen peroxide play important roles in cellular redox homeostasis and signaling. We used a hydrogen peroxide biosensor HyPer, targeted to different compartments, to examine these processes in mammalian cells. Principal Findings Reversible responses were observed to various redox perturbations and signaling events. HyPer expressed in HEK 293 cells was found to sense low micromolar levels of hydrogen peroxide. When targeted to various cellular ...

  11. Increase in cellular concrete resistance to brittle fracture

    International Nuclear Information System (INIS)

    Chernyshov, E.M.; Krokhin, A.M.

    1979-01-01

    Considered are theoretical premises of decrease in cellular concrete resistance to brittle fracture at the expense of dispersed reinforcement. It is stated experimentally that the introduction of 3% asbestos fibers permits to increase the ultimate extensibility and strength during cellular concrete tension by 15-30% and to increase in unit rupture work 1.4-1.6 time more and therefore to decrease its brittleness

  12. The cellular basis of skin injury after cytotoxic insult

    International Nuclear Information System (INIS)

    Potten, C.S.

    1986-01-01

    It is concluded that although the major target in terms of radiation damage is undoubtedly the epidermis, the skin is a complex tissue made up of many inter-dependent components each of which may constitute an important secondary target. Damage to each component has been considered at the cellular level. The precise inter-relationships and interdependencies remain somewhat obscure. Even within one site, the epidermis, a comprehensive cellular explanation of the various post-irradiation changes is difficult. Substantial bibliography. (UK)

  13. Cellular Basis for ADT-Induced Acceleration of Sarcopenia

    Science.gov (United States)

    2015-10-01

    1 AWARD NUMBER: W81XWH-14-1-0454 TITLE: Cellular Basis for ADT-Induced Acceleration of Sarcopenia PRINCIPAL INVESTIGATOR: Joe V...AND SUBTITLE Cellular Basis for ADT-Induced Acceleration of Sarcopenia 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-14-1-0454 5c. PROGRAM...cell function and thereby regenerative capability contribute to the acceleration of sarcopenia observed in prostate cancer patients undergoing ADT

  14. Uncovering the footprints of malicious traffic in cellular data networks

    OpenAIRE

    Raghuramu, A; Zang, H; Chuah, CN

    2015-01-01

    © Springer International Publishing Switzerland 2015. In this paper, we present a comprehensive characterization of malicious traffic generated by mobile devices using Deep Packet Inspection (DPI) records and security event logs from a large US based cellular provider network. Our analysis reveals that 0.17% of mobile devices in the cellular network are affected by security threats. This proportion, while small, is orders of magnitude higher than the last reported (in 2013) infection rate of ...

  15. Substructure formation in iron-nickel monocrystals at cellular growth

    International Nuclear Information System (INIS)

    Agapova, E.V.; Tagirova, D.M.

    1984-01-01

    Substructural perfection of Fe-31 wt.% Ni alloy crystals prepared by the Bridgeman method is investigated. Characteristics of banded and cellular structures at different morphology of crystallization front corresponding to the rates of growth (7.0-24.7)x10 -4 cm/s are determined. Position of disorientation axis of banded fragments is shown to depend on orientation of a groWing crystal and its strong fragmentation results in formation of finer cellular structure

  16. Cellular telephone use among primary school children in Germany

    International Nuclear Information System (INIS)

    Boehler, Eva; Schuez, Joachim

    2004-01-01

    Background: There is some concern about potential health risks of cellular telephone use to children. We assessed data on how many children own a cellular telephone and on how often they use it in a population-based sample. Methods: We carried out a cross-sectional study among children in their fourth elementary school year, with a median-age of 10 years. The study was carried out in Mainz (Germany), a city with about 200,000 inhabitants. The study base comprised all 37 primary schools in Mainz and near surroundings. Altogether, 1933 children from 34 primary schools took part in the survey (participation rate of 87.8%). Results: Roughly a third of all children (n = 671, 34.7%) reported to own a cellular telephone. Overall, 119 (6.2%) children used a cellular telephone for making calls at least once a day, 123 (6.4%) used it several times a week and 876 (45.3%) children used it only once in a while. The remaining 805 (41.6%) children had never used a cellular telephone. The probability of owning a cellular telephone among children was associated with older age, being male, having no siblings, giving full particulars to height and weight, more time spent watching TV and playing computer games, being picked up by their parents from school by car (instead of walking or cycling) and going to bed late. The proportion of cellular telephone owners was somewhat higher in classes with more children from socially disadvantaged families. Conclusions: Our study shows that both ownership of a cellular telephone as well as the regular use of it are already quite frequent among children in the fourth grade of primary school. With regard to potential long-term effects, we recommend follow-up studies with children

  17. PASSENGER TRAFFIC MOVEMENT MODELLING BY THE CELLULAR-AUTOMAT APPROACH

    Directory of Open Access Journals (Sweden)

    T. Mikhaylovskaya

    2009-01-01

    Full Text Available The mathematical model of passenger traffic movement developed on the basis of the cellular-automat approach is considered. The program realization of the cellular-automat model of pedastrians streams movement in pedestrian subways at presence of obstacles, at subway structure narrowing is presented. The optimum distances between the obstacles and the angle of subway structure narrowing providing pedastrians stream safe movement and traffic congestion occurance are determined.

  18. Peculiarities of hardware implementation of generalized cellular tetra automaton

    OpenAIRE

    Аноприенко, Александр Яковлевич; Федоров, Евгений Евгениевич; Иваница, Сергей Васильевич; Альрабаба, Хамза

    2015-01-01

    Cellular automata are widely used in many fields of knowledge for the study of variety of complex real processes: computer engineering and computer science, cryptography, mathematics, physics, chemistry, ecology, biology, medicine, epidemiology, geology, architecture, sociology, theory of neural networks. Thus, cellular automata (CA) and tetra automata are gaining relevance taking into account the hardware and software solutions.Also it is marked a trend towards an increase in the number of p...

  19. Design Optimization of Irregular Cellular Structure for Additive Manufacturing

    Science.gov (United States)

    Song, Guo-Hua; Jing, Shi-Kai; Zhao, Fang-Lei; Wang, Ye-Dong; Xing, Hao; Zhou, Jing-Tao

    2017-09-01

    Irregularcellular structurehas great potential to be considered in light-weight design field. However, the research on optimizing irregular cellular structures has not yet been reporteddue to the difficulties in their modeling technology. Based on the variable density topology optimization theory, an efficient method for optimizing the topology of irregular cellular structures fabricated through additive manufacturing processes is proposed. The proposed method utilizes tangent circles to automatically generate the main outline of irregular cellular structure. The topological layoutof each cellstructure is optimized using the relative density informationobtained from the proposed modified SIMP method. A mapping relationship between cell structure and relative densityelement is builtto determine the diameter of each cell structure. The results show that the irregular cellular structure can be optimized with the proposed method. The results of simulation and experimental test are similar for irregular cellular structure, which indicate that the maximum deformation value obtained using the modified Solid Isotropic Microstructures with Penalization (SIMP) approach is lower 5.4×10-5 mm than that using the SIMP approach under the same under the same external load. The proposed research provides the instruction to design the other irregular cellular structure.

  20. Role of cellular adhesions in tissue dynamics spectroscopy

    Science.gov (United States)

    Merrill, Daniel A.; An, Ran; Turek, John; Nolte, David

    2014-02-01

    Cellular adhesions play a critical role in cell behavior, and modified expression of cellular adhesion compounds has been linked to various cancers. We tested the role of cellular adhesions in drug response by studying three cellular culture models: three-dimensional tumor spheroids with well-developed cellular adhesions and extracellular matrix (ECM), dense three-dimensional cell pellets with moderate numbers of adhesions, and dilute three-dimensional cell suspensions in agarose having few adhesions. Our technique for measuring the drug response for the spheroids and cell pellets was biodynamic imaging (BDI), and for the suspensions was quasi-elastic light scattering (QELS). We tested several cytoskeletal chemotherapeutic drugs (nocodazole, cytochalasin-D, paclitaxel, and colchicine) on three cancer cell lines chosen from human colorectal adenocarcinoma (HT-29), human pancreatic carcinoma (MIA PaCa-2), and rat osteosarcoma (UMR-106) to exhibit differences in adhesion strength. Comparing tumor spheroid behavior to that of cell suspensions showed shifts in the spectral motion of the cancer tissues that match predictions based on different degrees of cell-cell contacts. The HT-29 cell line, which has the strongest adhesions in the spheroid model, exhibits anomalous behavior in some cases. These results highlight the importance of using three-dimensional tissue models in drug screening with cellular adhesions being a contributory factor in phenotypic differences between the drug responses of tissue and cells.

  1. Combinatorial approaches to evaluate nanodiamond uptake and induced cellular fate

    Science.gov (United States)

    Eldawud, Reem; Reitzig, Manuela; Opitz, Jörg; Rojansakul, Yon; Jiang, Wenjuan; Nangia, Shikha; Zoica Dinu, Cerasela

    2016-02-01

    Nanodiamonds (NDs) are an emerging class of engineered nanomaterials that hold great promise for the next generation of bionanotechnological products to be used for drug and gene delivery, or for bio-imaging and biosensing. Previous studies have shown that upon their cellular uptake, NDs exhibit high biocompatibility in various in vitro and in vivo set-ups. Herein we hypothesized that the increased NDs biocompatibility is a result of minimum membrane perturbations and their reduced ability to induce disruption or damage during cellular translocation. Using multi-scale combinatorial approaches that simulate ND-membrane interactions, we correlated NDs real-time cellular uptake and kinetics with the ND-induced membrane fluctuations to derive energy requirements for the uptake to occur. Our discrete and real-time analyses showed that the majority of NDs internalization occurs within 2 h of cellular exposure, however, with no effects on cellular viability, proliferation or cellular behavior. Furthermore, our simulation analyses using coarse-grained models identified key changes in the energy profile, membrane deformation and recovery time, all functions of the average ND or ND-based agglomerate size. Understanding the mechanisms responsible for ND-cell membrane interactions could possibly advance their implementation in various biomedical applications.

  2. Combinatorial approaches to evaluate nanodiamond uptake and induced cellular fate

    Science.gov (United States)

    Eldawud, Reem; Reitzig, Manuela; Opitz, Jörg; Rojansakul, Yon; Jiang, Wenjuan; Nangia, Shikha; Dinu, Cerasela Zoica

    2016-01-01

    Nanodiamonds (NDs) are an emerging class of engineered nanomaterials that hold great promise for the next generation of bionanotechnological products to be used for drug and gene delivery, or for bio-imaging and biosensing. Previous studies have shown that upon their cellular uptake, NDs exhibit high biocompatibility in various in vitro and in vivo set-ups. Herein we hypothesized that the increased NDs biocompatibility is a result of minimum membrane perturbations and their reduced ability to induce disruption or damage during cellular translocation. Using multi-scale combinatorial approaches that simulate ND-membrane interactions, we correlated NDs real-time cellular uptake and kinetics with the ND-induced membrane fluctuations to derive energy requirements for the uptake to occur. Our discrete and real-time analyses showed that the majority of NDs internalization occurs within 2 h of cellular exposure, however, with no effects on cellular viability, proliferation or cellular behavior. Furthermore, our simulation analyses using coarse-grained models identified key changes in the energy profile, membrane deformation and recovery time, all functions of the average ND or ND-based agglomerate size. Understanding the mechanisms responsible for ND-cell membrane interactions could possibly advance their implementation in various biomedical applications. PMID:26820775

  3. Force control for mechanoinduction of impedance variation in cellular organisms

    International Nuclear Information System (INIS)

    Nam, Joo Hoo; Chen, Peter C Y; Lu, Zhe; Luo, Hong; Lin, Wei; Ge, Ruowen

    2010-01-01

    Constantly exposed to various forms of mechanical forces inherent in their physical environment (such as gravity, stress induced by fluid flow or cell–cell interactions, etc), cellular organisms sense such forces and convert them into biochemical signals through the processes of mechanosensing and mechanotransduction that eventually lead to biological changes. The effect of external forces on the internal structures and activities in a cellular organism may manifest in changes its physical properties, such as impedance. Studying variation in the impedance of a cellular organism induced by the application of an external mechanical force represents a meaningful endeavor (from a biosystems perspective) in exploring the complex mechanosensing and mechanotransduction mechanisms that govern the behavior of a cellular organism under the influence of external mechanical stimuli. In this paper we describe the development of an explicit force-feedback control system for exerting an indentation force on a cellular organism while simultaneously measuring its impedance. To demonstrate the effectiveness of this force-control system, we have conducted experiments using zebrafish embryos as a test model of a cellular organism. We report experimental results demonstrating that the application of a properly controlled external force leads to a significant change in the impedance of a zebrafish embryo. These results offer support for a plausible explanation that activities of pore canals in the chorion are responsible for the observed change in impedance.

  4. Cellular phone interference with the operation of mechanical ventilators.

    Science.gov (United States)

    Shaw, Cheryl I; Kacmarek, Robert M; Hampton, Rickey L; Riggi, Vincent; El Masry, Ashraf; Cooper, Jeffrey B; Hurford, William E

    2004-04-01

    To determine whether a cellular phone would interfere with the operation of mechanical ventilators. Laboratory study. University medical center. Fourteen mechanical ventilators. We evaluated change in operation and malfunction of the mechanical ventilators. The cellular phone (Nokia 6120i) was computer controlled, operating at 828.750 MHz analog modulation. It was operated at 16, 40, 100, 250, and 600 mW, 30 cm from the floor and 30, 15, and ventilator. Six of the 14 ventilators tested malfunctioned when a cellular phone at maximum power output was placed ventilating when the cellular phone at maximum power output was placed ventilator. One ventilator doubled the ventilatory rate and another increased the displayed tidal volume from 350 to 1033 mL. In one of the infant ventilators, displayed tidal volume increased from 21 to 100 mL. In another ventilator, the high respiratory rate alarm sounded but the rate had not changed. In a controlled laboratory setting, cellular phones placed in close proximity to some commercially available intensive care ventilators can cause malfunctions, including irrecoverable cessation of ventilation. This is most likely to occur if the cellular phone is or =3 feet from all medical devices. The current electromagnetic compatibility standards for mechanical ventilators are inadequate to prevent malfunction. Manufacturers should ensure that their products are not affected by wireless technology even when placed immediately next to the device.

  5. Combinatorial approaches to evaluate nanodiamond uptake and induced cellular fate

    International Nuclear Information System (INIS)

    Eldawud, Reem; Dinu, Cerasela Zoica; Reitzig, Manuela; Opitz, Jörg; Rojansakul, Yon; Jiang, Wenjuan; Nangia, Shikha

    2016-01-01

    Nanodiamonds (NDs) are an emerging class of engineered nanomaterials that hold great promise for the next generation of bionanotechnological products to be used for drug and gene delivery, or for bio-imaging and biosensing. Previous studies have shown that upon their cellular uptake, NDs exhibit high biocompatibility in various in vitro and in vivo set-ups. Herein we hypothesized that the increased NDs biocompatibility is a result of minimum membrane perturbations and their reduced ability to induce disruption or damage during cellular translocation. Using multi-scale combinatorial approaches that simulate ND-membrane interactions, we correlated NDs real-time cellular uptake and kinetics with the ND-induced membrane fluctuations to derive energy requirements for the uptake to occur. Our discrete and real-time analyses showed that the majority of NDs internalization occurs within 2 h of cellular exposure, however, with no effects on cellular viability, proliferation or cellular behavior. Furthermore, our simulation analyses using coarse-grained models identified key changes in the energy profile, membrane deformation and recovery time, all functions of the average ND or ND-based agglomerate size. Understanding the mechanisms responsible for ND-cell membrane interactions could possibly advance their implementation in various biomedical applications. (paper)

  6. Combinatorial approaches to evaluate nanodiamond uptake and induced cellular fate.

    Science.gov (United States)

    Eldawud, Reem; Reitzig, Manuela; Opitz, Jörg; Rojansakul, Yon; Jiang, Wenjuan; Nangia, Shikha; Dinu, Cerasela Zoica

    2016-02-26

    Nanodiamonds (NDs) are an emerging class of engineered nanomaterials that hold great promise for the next generation of bionanotechnological products to be used for drug and gene delivery, or for bio-imaging and biosensing. Previous studies have shown that upon their cellular uptake, NDs exhibit high biocompatibility in various in vitro and in vivo set-ups. Herein we hypothesized that the increased NDs biocompatibility is a result of minimum membrane perturbations and their reduced ability to induce disruption or damage during cellular translocation. Using multi-scale combinatorial approaches that simulate ND-membrane interactions, we correlated NDs real-time cellular uptake and kinetics with the ND-induced membrane fluctuations to derive energy requirements for the uptake to occur. Our discrete and real-time analyses showed that the majority of NDs internalization occurs within 2 h of cellular exposure, however, with no effects on cellular viability, proliferation or cellular behavior. Furthermore, our simulation analyses using coarse-grained models identified key changes in the energy profile, membrane deformation and recovery time, all functions of the average ND or ND-based agglomerate size. Understanding the mechanisms responsible for ND-cell membrane interactions could possibly advance their implementation in various biomedical applications.

  7. Lipids, lipid droplets and lipoproteins in their cellular context; an ultrastructural approach

    NARCIS (Netherlands)

    Mesman, R.J.

    2013-01-01

    Lipids are essential for cellular life, functioning either organized as bilayer membranes to compartmentalize cellular processes, as signaling molecules or as metabolic energy storage. Our current knowledge on lipid organization and cellular lipid homeostasis is mainly based on biochemical data.

  8. 77 FR 71194 - Draft Guidance for Industry: Preclinical Assessment of Investigational Cellular and Gene Therapy...

    Science.gov (United States)

    2012-11-29

    ...] Draft Guidance for Industry: Preclinical Assessment of Investigational Cellular and Gene Therapy... Industry: Preclinical Assessment of Investigational Cellular and Gene Therapy Products,'' dated November... Evaluation (CBER), Office of Cellular, Tissue, and Gene Therapies (OCTGT). The product areas covered by this...

  9. Cellular energy allocation in zebra mussels exposed along a pollution gradient: linking cellular effects to higher levels of biological organization.

    Science.gov (United States)

    Smolders, R; Bervoets, L; De Coen, W; Blust, R

    2004-05-01

    Organisms exposed to suboptimal environments incur a cost of dealing with stress in terms of metabolic resources. The total amount of energy available for maintenance, growth and reproduction, based on the biochemical analysis of the energy budget, may provide a sensitive measure of stress in an organism. While the concept is clear, linking cellular or biochemical responses to the individual and population or community level remains difficult. The aim of this study was to validate, under field conditions, using cellular energy budgets [i.e. changes in glycogen-, lipid- and protein-content and mitochondrial electron transport system (ETS)] as an ecologically relevant measurement of stress by comparing these responses to physiological and organismal endpoints. Therefore, a 28-day in situ bioassay with zebra mussels (Dreissena polymorpha) was performed in an effluent-dominated stream. Five locations were selected along the pollution gradient and compared with a nearby (reference) site. Cellular Energy Allocation (CEA) served as a biomarker of cellular energetics, while Scope for Growth (SFG) indicated effects on a physiological level and Tissue Condition Index and wet tissue weight/dry tissue weight ratio were used as endpoints of organismal effects. Results indicated that energy budgets at a cellular level of biological organization provided the fastest and most sensitive response and energy budgets are a relevant currency to extrapolate cellular effects to higher levels of biological organization within the exposed mussels.

  10. Creating the Chemistry in Cellular Respiration Concept Inventory (CCRCI)

    Science.gov (United States)

    Forshee, Jay Lance, II

    Students at our institution report cellular respiration to be the most difficult concept they encounter in undergraduate biology, but why students find this difficult is unknown. Students may find cellular respiration difficult because there is a large amount of steps, or because there are persistent, long-lasting misconceptions and misunderstandings surrounding their knowledge of chemistry, which affect their performance on cellular respiration assessments. Most studies of cellular respiration focus on student macro understanding of the process related to breathing, and matter and energy. To date, no studies identify which chemistry concepts are most relevant to students' development of an understanding of the process of cellular respiration or have developed an assessment to measure student understanding of them. Following the Delphi method, the researchers conducted expert interviews with faculty members from four-year, masters-, and PhD-granting institutions who teach undergraduate general biology, and are experts in their respective fields of biology. From these interviews, researchers identified twelve chemistry concepts important to understanding cellular respiration and using surveys, these twelve concepts were refined into five (electron transfer, energy transfer, thermodynamics (law/conservation), chemical reactions, and gradients). The researchers then interviewed undergraduate introductory biology students at a large Midwestern university to identify their knowledge and misconceptions of the chemistry concepts that the faculty had identified previously as important. The CCRCI was developed using the five important chemistry concepts underlying cellular respiration. The final version of the CCRCI was administered to n=160 introductory biology students during the spring 2017 semester. Reliability of the CCRCI was evaluated using Cronbach's alpha (=.7) and split-half reliability (=.769), and validity of the instrument was assessed through content validity

  11. Handover management in dense cellular networks: A stochastic geometry approach

    KAUST Repository

    Arshad, Rabe; Elsawy, Hesham; Sorour, Sameh; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2016-01-01

    Cellular operators are continuously densifying their networks to cope with the ever-increasing capacity demand. Furthermore, an extreme densification phase for cellular networks is foreseen to fulfill the ambitious fifth generation (5G) performance requirements. Network densification improves spectrum utilization and network capacity by shrinking base stations' (BSs) footprints and reusing the same spectrum more frequently over the spatial domain. However, network densification also increases the handover (HO) rate, which may diminish the capacity gains for mobile users due to HO delays. In highly dense 5G cellular networks, HO delays may neutralize or even negate the gains offered by network densification. In this paper, we present an analytical paradigm, based on stochastic geometry, to quantify the effect of HO delay on the average user rate in cellular networks. To this end, we propose a flexible handover scheme to reduce HO delay in case of highly dense cellular networks. This scheme allows skipping the HO procedure with some BSs along users' trajectories. The performance evaluation and testing of this scheme for only single HO skipping shows considerable gains in many practical scenarios. © 2016 IEEE.

  12. An improved cellular automaton method to model multispecies biofilms.

    Science.gov (United States)

    Tang, Youneng; Valocchi, Albert J

    2013-10-01

    Biomass-spreading rules used in previous cellular automaton methods to simulate multispecies biofilm introduced extensive mixing between different biomass species or resulted in spatially discontinuous biomass concentration and distribution; this caused results based on the cellular automaton methods to deviate from experimental results and those from the more computationally intensive continuous method. To overcome the problems, we propose new biomass-spreading rules in this work: Excess biomass spreads by pushing a line of grid cells that are on the shortest path from the source grid cell to the destination grid cell, and the fractions of different biomass species in the grid cells on the path change due to the spreading. To evaluate the new rules, three two-dimensional simulation examples are used to compare the biomass distribution computed using the continuous method and three cellular automaton methods, one based on the new rules and the other two based on rules presented in two previous studies. The relationship between the biomass species is syntrophic in one example and competitive in the other two examples. Simulation results generated using the cellular automaton method based on the new rules agree much better with the continuous method than do results using the other two cellular automaton methods. The new biomass-spreading rules are no more complex to implement than the existing rules. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. High-strength cellular ceramic composites with 3D microarchitecture.

    Science.gov (United States)

    Bauer, Jens; Hengsbach, Stefan; Tesari, Iwiza; Schwaiger, Ruth; Kraft, Oliver

    2014-02-18

    To enhance the strength-to-weight ratio of a material, one may try to either improve the strength or lower the density, or both. The lightest solid materials have a density in the range of 1,000 kg/m(3); only cellular materials, such as technical foams, can reach considerably lower values. However, compared with corresponding bulk materials, their specific strength generally is significantly lower. Cellular topologies may be divided into bending- and stretching-dominated ones. Technical foams are structured randomly and behave in a bending-dominated way, which is less weight efficient, with respect to strength, than stretching-dominated behavior, such as in regular braced frameworks. Cancellous bone and other natural cellular solids have an optimized architecture. Their basic material is structured hierarchically and consists of nanometer-size elements, providing a benefit from size effects in the material strength. Designing cellular materials with a specific microarchitecture would allow one to exploit the structural advantages of stretching-dominated constructions as well as size-dependent strengthening effects. In this paper, we demonstrate that such materials may be fabricated. Applying 3D laser lithography, we produced and characterized micro-truss and -shell structures made from alumina-polymer composite. Size-dependent strengthening of alumina shells has been observed, particularly when applied with a characteristic thickness below 100 nm. The presented artificial cellular materials reach compressive strengths up to 280 MPa with densities well below 1,000 kg/m(3).

  14. Handover management in dense cellular networks: A stochastic geometry approach

    KAUST Repository

    Arshad, Rabe

    2016-07-26

    Cellular operators are continuously densifying their networks to cope with the ever-increasing capacity demand. Furthermore, an extreme densification phase for cellular networks is foreseen to fulfill the ambitious fifth generation (5G) performance requirements. Network densification improves spectrum utilization and network capacity by shrinking base stations\\' (BSs) footprints and reusing the same spectrum more frequently over the spatial domain. However, network densification also increases the handover (HO) rate, which may diminish the capacity gains for mobile users due to HO delays. In highly dense 5G cellular networks, HO delays may neutralize or even negate the gains offered by network densification. In this paper, we present an analytical paradigm, based on stochastic geometry, to quantify the effect of HO delay on the average user rate in cellular networks. To this end, we propose a flexible handover scheme to reduce HO delay in case of highly dense cellular networks. This scheme allows skipping the HO procedure with some BSs along users\\' trajectories. The performance evaluation and testing of this scheme for only single HO skipping shows considerable gains in many practical scenarios. © 2016 IEEE.

  15. Bioinspired Cellular Structures: Additive Manufacturing and Mechanical Properties

    Science.gov (United States)

    Stampfl, J.; Pettermann, H. E.; Liska, R.

    Biological materials (e.g., wood, trabecular bone, marine skeletons) rely heavily on the use of cellular architecture, which provides several advantages. (1) The resulting structures can bear the variety of "real life" load spectra using a minimum of a given bulk material, featuring engineering lightweight design principles. (2) The inside of the structures is accessible to body fluids which deliver the required nutrients. (3) Furthermore, cellular architectures can grow organically by adding or removing individual struts or by changing the shape of the constituting elements. All these facts make the use of cellular architectures a reasonable choice for nature. Using additive manufacturing technologies (AMT), it is now possible to fabricate such structures for applications in engineering and biomedicine. In this chapter, we present methods that allow the 3D computational analysis of the mechanical properties of cellular structures with open porosity. Various different cellular architectures including disorder are studied. In order to quantify the influence of architecture, the apparent density is always kept constant. Furthermore, it is shown that how new advanced photopolymers can be used to tailor the mechanical and functional properties of the fabricated structures.

  16. Cellular solutions for the Poisson equation in extended systems

    International Nuclear Information System (INIS)

    Zhang, X.; Butler, W.H.; MacLaren, J.M.; van Ek, J.

    1994-01-01

    The Poisson equation for the electrostatic potential in a solid is solved using three different cellular techniques. The relative merits of these different approaches are discussed for two test charge densities for which an analytic solution to the Poisson equation is known. The first approach uses full-cell multiple-scattering theory and results in the famililar structure constant and multipole moment expansion. This solution is shown to be valid everywhere inside the cell, although for points outside the muffin-tin sphere but inside the cell the sums must be performed in the correct order to yield meaningful results. A modification of the multiple-scattering-theory approach yields a second method, a Green-function cellular method, which only requires the solution of a nearest-neighbor linear system of equations. A third approach, a related variational cellular method, is also derived. The variational cellular approach is shown to be the most accurate and reliable, and to have the best convergence in angular momentum of the three methods. Coulomb energies accurate to within 10 -6 hartree are easily achieved with the variational cellular approach, demonstrating the practicality of the approach in electronic structure calculations

  17. Cellular energy allocation in zebra mussels exposed along a pollution gradient: linking cellular effects to higher levels of biological organization

    International Nuclear Information System (INIS)

    Smolders, R.; Bervoets, L.; Coen, W. de; Blust, R.

    2004-01-01

    Organisms exposed to suboptimal environments incur a cost of dealing with stress in terms of metabolic resources. The total amount of energy available for maintenance, growth and reproduction, based on the biochemical analysis of the energy budget, may provide a sensitive measure of stress in an organism. While the concept is clear, linking cellular or biochemical responses to the individual and population or community level remains difficult. The aim of this study was to validate, under field conditions, using cellular energy budgets [i.e. changes in glycogen-, lipid- and protein-content and mitochondrial electron transport system (ETS)] as an ecologically relevant measurement of stress by comparing these responses to physiological and organismal endpoints. Therefore, a 28-day in situ bioassay with zebra mussels (Dreissena polymorpha) was performed in an effluent-dominated stream. Five locations were selected along the pollution gradient and compared with a nearby (reference) site. Cellular Energy Allocation (CEA) served as a biomarker of cellular energetics, while Scope for Growth (SFG) indicated effects on a physiological level and Tissue Condition Index and wet tissue weight/dry tissue weight ratio were used as endpoints of organismal effects. Results indicated that energy budgets at a cellular level of biological organization provided the fastest and most sensitive response and energy budgets are a relevant currency to extrapolate cellular effects to higher levels of biological organization within the exposed mussels. - Exposure of zebra mussels along a pollution gradient has adverse effects on the cellular energy allocation, and results can be linked with higher levels of biological organization

  18. Cellular energy allocation in zebra mussels exposed along a pollution gradient: linking cellular effects to higher levels of biological organization

    Energy Technology Data Exchange (ETDEWEB)

    Smolders, R.; Bervoets, L.; Coen, W. de; Blust, R

    2004-05-01

    Organisms exposed to suboptimal environments incur a cost of dealing with stress in terms of metabolic resources. The total amount of energy available for maintenance, growth and reproduction, based on the biochemical analysis of the energy budget, may provide a sensitive measure of stress in an organism. While the concept is clear, linking cellular or biochemical responses to the individual and population or community level remains difficult. The aim of this study was to validate, under field conditions, using cellular energy budgets [i.e. changes in glycogen-, lipid- and protein-content and mitochondrial electron transport system (ETS)] as an ecologically relevant measurement of stress by comparing these responses to physiological and organismal endpoints. Therefore, a 28-day in situ bioassay with zebra mussels (Dreissena polymorpha) was performed in an effluent-dominated stream. Five locations were selected along the pollution gradient and compared with a nearby (reference) site. Cellular Energy Allocation (CEA) served as a biomarker of cellular energetics, while Scope for Growth (SFG) indicated effects on a physiological level and Tissue Condition Index and wet tissue weight/dry tissue weight ratio were used as endpoints of organismal effects. Results indicated that energy budgets at a cellular level of biological organization provided the fastest and most sensitive response and energy budgets are a relevant currency to extrapolate cellular effects to higher levels of biological organization within the exposed mussels. - Exposure of zebra mussels along a pollution gradient has adverse effects on the cellular energy allocation, and results can be linked with higher levels of biological organization.

  19. Empirical study on entropy models of cellular manufacturing systems

    Institute of Scientific and Technical Information of China (English)

    Zhifeng Zhang; Renbin Xiao

    2009-01-01

    From the theoretical point of view,the states of manufacturing resources can be monitored and assessed through the amount of information needed to describe their technological structure and operational state.The amount of information needed to describe cellular manufacturing systems is investigated by two measures:the structural entropy and the operational entropy.Based on the Shannon entropy,the models of the structural entropy and the operational entropy of cellular manufacturing systems are developed,and the cognizance of the states of manufacturing resources is also illustrated.Scheduling is introduced to measure the entropy models of cellular manufacturing systems,and the feasible concepts of maximum schedule horizon and schedule adherence are advanced to quantitatively evaluate the effectiveness of schedules.Finally,an example is used to demonstrate the validity of the proposed methodology.

  20. Cellular automaton-based position sensitive detector equalization

    Energy Technology Data Exchange (ETDEWEB)

    Ferrando, Nestor [Grupo de Diseno de Sistemas Digitales, Instituto de Aplicaciones de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)], E-mail: nesferjo@upvnet.upv.es; Herrero, V.; Cerda, J.; Lerche, C.W.; Colom, R.J.; Gadea, R.; Martinez, J.D.; Monzo, J.M.; Mateo, F.; Sebastia, A.; Benlloch, J.M. [Grupo de Diseno de Sistemas Digitales, Instituto de Aplicaciones de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

    2009-06-01

    Indirect position detectors based on scintillator crystals lack of spacial uniformity in their response. This happens due to crystal inhomogeneities and gain differences among the photomultiplier anodes. In order to solve this, PESIC, an integrated front-end for multianode photomultiplier based nuclear imaging devices was created. One of its main features is the digitally programmable gain adjustment for every photomultiplier output. On another front, cellular automata have been proved to be a useful method for dynamic system modeling. In this paper, a cellular automaton which emulates the behavior of the scintillator crystal, the photomultiplier and the front-end is introduced. Thanks to this model, an automatic energy-based calibration of the detector can be done by configuring the cellular automaton with experimental data and making it evolve up to an stable state. This can be useful as a precalibration method of the detector.

  1. Thermo-fluid behaviour of periodic cellular metals

    CERN Document Server

    Lu, Tian Jian; Wen, Ting

    2013-01-01

    Thermo-Fluid Behaviour of Periodic Cellular Metals introduces the study of coupled thermo-fluid behaviour of cellular metals with periodic structure in response to thermal loads, which is an interdisciplinary research area that requires a concurrent-engineering approach.  The book, for the first time, systematically adopts experimental, numerical, and analytical approaches, presents the fluid flow and heat transfer in periodic cellular metals under forced convection conditions, aiming to establish structure-property relationships for tailoring material structures to achieve properties and performance levels that are customized for defined multifunctional applications. The book, as a textbook and reference book, is intended for both academic and industrial people, including graduate students, researchers and engineers. Dr. Tian Jian Lu is a professor at the School of Aerospace, Xi’an Jiaotong University, Xi’an, China. Dr. Feng Xu is a professor at the Key Laboratory of Biomedical Information Engineering o...

  2. Error performance analysis in downlink cellular networks with interference management

    KAUST Repository

    Afify, Laila H.

    2015-05-01

    Modeling aggregate network interference in cellular networks has recently gained immense attention both in academia and industry. While stochastic geometry based models have succeeded to account for the cellular network geometry, they mostly abstract many important wireless communication system aspects (e.g., modulation techniques, signal recovery techniques). Recently, a novel stochastic geometry model, based on the Equivalent-in-Distribution (EiD) approach, succeeded to capture the aforementioned communication system aspects and extend the analysis to averaged error performance, however, on the expense of increasing the modeling complexity. Inspired by the EiD approach, the analysis developed in [1] takes into consideration the key system parameters, while providing a simple tractable analysis. In this paper, we extend this framework to study the effect of different interference management techniques in downlink cellular network. The accuracy of the proposed analysis is verified via Monte Carlo simulations.

  3. Cellular blebs: pressure-driven, axisymmetric, membrane protrusions

    KAUST Repository

    Woolley, Thomas E.

    2013-07-16

    Blebs are cellular protrusions that are used by cells for multiple purposes including locomotion. A mechanical model for the problem of pressure-driven blebs based on force and moment balances of an axisymmetric shell model is proposed. The formation of a bleb is initiated by weakening the shell over a small region, and the deformation of the cellular membrane from the cortex is obtained during inflation. However, simply weakening the shell leads to an area increase of more than 4 %, which is physically unrealistic. Thus, the model is extended to include a reconfiguration process that allows large blebs to form with small increases in area. It is observed that both geometric and biomechanical constraints are important in this process. In particular, it is shown that although blebs are driven by a pressure difference across the cellular membrane, it is not the limiting factor in determining bleb size. © 2013 Springer-Verlag Berlin Heidelberg.

  4. Tissue Engineering Strategies for Myocardial Regeneration: Acellular Versus Cellular Scaffolds?

    Science.gov (United States)

    Domenech, Maribella; Polo-Corrales, Lilliana; Ramirez-Vick, Jaime E; Freytes, Donald O

    2016-12-01

    Heart disease remains one of the leading causes of death in industrialized nations with myocardial infarction (MI) contributing to at least one fifth of the reported deaths. The hypoxic environment eventually leads to cellular death and scar tissue formation. The scar tissue that forms is not mechanically functional and often leads to myocardial remodeling and eventual heart failure. Tissue engineering and regenerative medicine principles provide an alternative approach to restoring myocardial function by designing constructs that will restore the mechanical function of the heart. In this review, we will describe the cellular events that take place after an MI and describe current treatments. We will also describe how biomaterials, alone or in combination with a cellular component, have been used to engineer suitable myocardium replacement constructs and how new advanced culture systems will be required to achieve clinical success.

  5. Cellular Response to Ionizing Radiation: A MicroRNA Story

    Science.gov (United States)

    Halimi, Mohammad; Asghari, S. Mohsen; Sariri, Reyhaneh; Moslemi, Dariush; Parsian, Hadi

    2012-01-01

    MicroRNAs (miRNAs) represent a class of small non-coding RNA molecules that regulate gene expression at the post-transcriptional level. They play a crucial role in diverse cellular pathways. Ionizing radiation (IR) is one of the most important treatment protocols for patients that suffer from cancer and affects directly or indirectly cellular integration. Recently it has been discovered that microRNA-mediated gene regulation interferes with radio-related pathways in ionizing radiation. Here, we review the recent discoveries about miRNAs in cellular response to IR. Thoroughly understanding the mechanism of miRNAs in radiation response, it will be possible to design new strategies for improving radiotherapy efficiency and ultimately cancer treatment. PMID:24551775

  6. In vivo cellular imaging using fluorescent proteins - Methods and Protocols

    Directory of Open Access Journals (Sweden)

    M. Monti

    2012-12-01

    Full Text Available The discovery and genetic engineering of fluorescent proteins has revolutionized cell biology. What was previously invisible to the cell often can be made visible with the use of fluorescent proteins. With this words, Robert M. Hoffman introduces In vivo Cellular Imaging Using Fluorescent proteins, the eighteen chapters book dedicated to the description of how fluorescence proteins have changed the way to analyze cellular processes in vivo. Modern researches aim to study new and less invasive methods able to follow the behavior of different cell types in different biological contexts: for example, how cancer cells migrate or how they respond to different therapies. Also, in vivo systems can help researchers to better understand animal embryonic development so as how fluorescence proteins may be used to monitor different processes in living organisms at the molecular and cellular level.

  7. Lempel-Ziv complexity analysis of one dimensional cellular automata.

    Science.gov (United States)

    Estevez-Rams, E; Lora-Serrano, R; Nunes, C A J; Aragón-Fernández, B

    2015-12-01

    Lempel-Ziv complexity measure has been used to estimate the entropy density of a string. It is defined as the number of factors in a production factorization of a string. In this contribution, we show that its use can be extended, by using the normalized information distance, to study the spatiotemporal evolution of random initial configurations under cellular automata rules. In particular, the transfer information from time consecutive configurations is studied, as well as the sensitivity to perturbed initial conditions. The behavior of the cellular automata rules can be grouped in different classes, but no single grouping captures the whole nature of the involved rules. The analysis carried out is particularly appropriate for studying the computational processing capabilities of cellular automata rules.

  8. Cellular structures using U_q-tilting modules

    DEFF Research Database (Denmark)

    Andersen, Henning Haahr; Stroppel, Catharina; Tubbenhauer, Daniel

    We use the theory of Uq-tilting modules to construct cellular bases for centralizer algebras. Our methods are quite general and work for any quantum group Uq attached to a Cartan matrix and include the non semi-simple cases for q being a root of unity and ground fields of positive characteristic........ Our approach also generalize to certain categories containing infinite dimensional modules. As an application, we recover several known cellular structures (which can all be fit into our general set-up) as we illustrate in a list of examples.......We use the theory of Uq-tilting modules to construct cellular bases for centralizer algebras. Our methods are quite general and work for any quantum group Uq attached to a Cartan matrix and include the non semi-simple cases for q being a root of unity and ground fields of positive characteristic...

  9. Cellular structure of lean hydrogen flames in microgravity

    Science.gov (United States)

    Patnaik, G.; Kailasanath, K.

    1990-01-01

    Detailed, time-dependent, two-dimensional numerical simulations of premixed laminar flames have been used to study the initiation and subsequent development of cellular structures in lean hydrogen-air flames. The model includes detailed hydrogen-oxygen combustion with 24 elementary reactions of eight reactive species and a nitrogen diluent, molecular diffusion of all species, thermal conduction, viscosity, and convection. This model has been used to study the nonlinear evolution of cellular flame structure and shows that cell splitting, as observed in experiments, can be predicted numerically for sufficiently reactive mixtures. The structures that evolved also resembled the cellular structures observed in experiments. The present study shows that the 'cell-split limit' postulated from experimental observations is an intrinsic property of the mixture and that external factors such as heat losses are not necessary to cause this limit.

  10. Cellular 5G Access for Massive Internet of Things

    DEFF Research Database (Denmark)

    Madueño, Germán Corrales; Pratas, Nuno; Stefanovic, Cedomir

    2017-01-01

    The Internet of Things (IoT) refers to the paradigm of physical and virtual “things” that communicate and collaborate over the Internet, with minimal or no human intervention. There are multiple ways in which an IoT device can be connected to the Internet. Cellular technologies are seen as viable...... candidates in this respect, due to their maturity, worldwide availability and the use of reserved spectrum. However, current cellular systems are not well-equipped to efficiently and reliably support IoT traffic, particularly in the radio access part, as they are designed for low number of high......-rate connections and not for high number of low-rate IoT connections. In this chapter we outline the main features of the IoT traffic types, review operation of the current cellular access and provide some guidelines how to address its shortcomings and evolve it in order to support IoT services. However...

  11. Pathway towards Programmable Wave Anisotropy in Cellular Metamaterials

    Science.gov (United States)

    Celli, Paolo; Zhang, Weiting; Gonella, Stefano

    2018-01-01

    In this work, we provide a proof-of-concept experimental demonstration of the wave-control capabilities of cellular metamaterials endowed with populations of tunable electromechanical resonators. Each independently tunable resonator comprises a piezoelectric patch and a resistor-inductor shunt, and its resonant frequency can be seamlessly reprogrammed without interfering with the cellular structure's default properties. We show that, by strategically placing the resonators in the lattice domain and by deliberately activating only selected subsets of them, chosen to conform to the directional features of the beamed wave response, it is possible to override the inherent wave anisotropy of the cellular medium. The outcome is the establishment of tunable spatial patterns of energy distillation resulting in a nonsymmetric correction of the wave fields.

  12. Similarities of cellular receptors for interferon and cortisol

    International Nuclear Information System (INIS)

    Filipic, B.; Schauer, P.; Likar, M.

    1977-01-01

    Cellular receptors are molecules located on the cell membrane. Their function is to bind different molecules to the cell surface. These molecules can penetrate into the cytoplasm and trigger cellular changes. One kind of such bound molecules are interferons and corticosteroids. Until very recently very little was known about interferon's receptors on the cell surface, mechanisms of interferon's binding to them or about kinetics of such binding. On the basis of results published elsewhere and on the basis of experimental results, the authors suggest: receptors for interferon and cortisol are glycoproteins located on the cell surface, in analogy with PHA receptors they are chemically sialoglycoproteins, binding kinetics of cortisol and interferon is similar, interferon and cortisol compete for cellular receptors, binding of cortisol or interferon is dependent on allosteric configuration of receptor molecules. (author)

  13. Cellular automaton-based position sensitive detector equalization

    International Nuclear Information System (INIS)

    Ferrando, Nestor; Herrero, V.; Cerda, J.; Lerche, C.W.; Colom, R.J.; Gadea, R.; Martinez, J.D.; Monzo, J.M.; Mateo, F.; Sebastia, A.; Benlloch, J.M.

    2009-01-01

    Indirect position detectors based on scintillator crystals lack of spacial uniformity in their response. This happens due to crystal inhomogeneities and gain differences among the photomultiplier anodes. In order to solve this, PESIC, an integrated front-end for multianode photomultiplier based nuclear imaging devices was created. One of its main features is the digitally programmable gain adjustment for every photomultiplier output. On another front, cellular automata have been proved to be a useful method for dynamic system modeling. In this paper, a cellular automaton which emulates the behavior of the scintillator crystal, the photomultiplier and the front-end is introduced. Thanks to this model, an automatic energy-based calibration of the detector can be done by configuring the cellular automaton with experimental data and making it evolve up to an stable state. This can be useful as a precalibration method of the detector.

  14. Shock enhancement of cellular materials subjected to intensive pulse loading

    Science.gov (United States)

    Zhang, J.; Fan, J.; Wang, Z.; Zhao, L.; Li, Z.

    2018-03-01

    Cellular materials can dissipate a large amount of energy due to their considerable stress plateau, which contributes to their extensive applications in structural design for crashworthiness. However, in some experiments with specimens subjected to intense impact loads, transmitted stress enhancement has been observed, leading to severe damage to the objects protected. Transmitted stress through two-dimensional Voronoi cellular materials as a protective device is qualitatively studied in this paper. Dimensionless parameters of material properties and loading parameters are defined to give critical conditions for shock enhancement and clarify the correlation between the deformations and stress enhancement. The effect of relative density on this amplifying phenomenon is investigated as well. In addition, local strain fields are calculated by using the optimal local deformation gradient, which gives a clear presentation of deformations and possible local non-uniformity in the crushing process. This research provides valuable insight into the reliability of cellular materials as protective structures.

  15. Cellular roles of ADAM12 in health and disease

    DEFF Research Database (Denmark)

    Kveiborg, Marie; Albrechtsen, Reidar; Couchman, John R

    2008-01-01

    and it is a potential biomarker for breast cancer. It is therefore important to understand ADAM12's functions. Many cellular roles for ADAM12 have been suggested. It is an active metalloprotease, and has been implicated in insulin-like growth factor (IGF) receptor signaling, through cleavage of IGF-binding proteins......, and in epidermal growth factor receptor (EGFR) pathways, via ectodomain shedding of membrane-tethered EGFR ligands. These proteolytic events may regulate diverse cellular responses, such as altered cell differentiation, proliferation, migration, and invasion. ADAM12 may also regulate cell-cell and cell...... to or from the cell interior. These ADAM12-mediated cellular effects appear to be critical events in both biological and pathological processes. This review presents current knowledge on ADAM12 functions gained from in vitro and in vivo observations, describes ADAM12's role in both normal physiology...

  16. Pathogenesis of pulmonary emphysema – cellular and molecular events

    Directory of Open Access Journals (Sweden)

    Antonio Di Petta

    2010-06-01

    Full Text Available Pulmonary emphysema is a chronic obstructive disease, resulting fromimportant alterations in the whole distal structure of terminal bronchioles, either by enlargement of air spaces or by destruction of the alveolar wall, leading to loss of respiratory surface, decreased elastic recoil and lung hyperinflation. For many years, the hypothesis of protease-antiprotease unbalance prevailed as the central theme in the pathogenesis of pulmonary emphysema. According to this hypothesis, the release of active proteolytic enzymes, produced mainly by neutrophils and macrophages, degrades the extracellular matrix, affecting the integrity of its components, especially collagen and elastic fibers. However, new concepts involving cellular and molecular events were proposed, including oxidative stress, cell apoptosis, cellular senescence and failed lung tissue repair. The aim of this review paper was to evaluate the cellular and molecular mechanisms seen in the pathogenesis of pulmonary emphysema.

  17. Increasing cellular coverage within integrated terrestrial/satellite mobile networks

    Science.gov (United States)

    Castro, Jonathan P.

    1995-01-01

    When applying the hierarchical cellular concept, the satellite acts as giant umbrella cell covering a region with some terrestrial cells. If a mobile terminal traversing the region arrives to the border-line or limits of a regular cellular ground service, network transition occurs and the satellite system continues the mobile coverage. To adequately assess the boundaries of service of a mobile satellite system an a cellular network within an integrated environment, this paper provides an optimized scheme to predict when a network transition may be necessary. Under the assumption of a classified propagation phenomenon and Lognormal shadowing, the study applies an analytical approach to estimate the location of a mobile terminal based on a reception of the signal strength emitted by a base station.

  18. Cell activation and cellular-cellular interactions during hemodialysis: effect of dialyzer membrane.

    Science.gov (United States)

    Sirolli, V; Ballone, E; Di Stante, S; Amoroso, L; Bonomini, M

    2002-06-01

    During hemodialysis (HD), circulating blood cells can be activated and also engage in dynamic interplay. These phenomena may be important factors behind dialysis membrane bio(in)compatibility. In the present prospective cross-over study, we have used flow cytometry to evaluate the influence of different dialysis membranes on the activation of circulating blood cells (leukocytes, platelets) and their dynamic interactions (formation of circulating platelet-leukocyte and platelet-erythrocyte aggregates) during in vivo HD. Each patient (n = 10) was treated with dialyzers containing membranes of cellulose diacetate, polysulfone and ethylenevinylalcohol (EVAL) in a randomized order. Upregulation of adhesion receptor expression (CD15s, CD11b/CD18) occurred mainly with the cellulosic membrane, though an increase in CD11b/CD18 circulating on neutrophils was also found with both synthetic membranes. Circulating activated platelets (P-selectin/CD63-positive platelets) increased during HD sessions with cellulose diacetate and polysulfone. An increased formation of platelet-neutrophil aggregates was found at 15 and 30 min during dialysis with cellulose diacetate and polysulfone but not with EVAL. Platelet-erythrocyte aggregates also increased with cellulose diacetate and at 15 min with polysulfone as well. Generally in concomitance with the increase in platelet-neutrophil coaggregates, there was an increased hydrogen peroxide production by neutrophils. The results of this study indicate that cellular mechanisms can be activated during HD largely depending on the membrane material, EVAL causing less reactivity than the other two membranes. It appears that each dialysis membrane has multiple and different characteristics that may contribute to interactions with blood components. Our results also indicate that derivatizing cellulose (cellulose diacetate) may be a useful way to improve the biocompatibility of the cellulose polymer and that there may be great variability in the

  19. The similia principle: results obtained in a cellular model system.

    Science.gov (United States)

    Wiegant, Fred; Van Wijk, Roeland

    2010-01-01

    This paper describes the results of a research program focused on the beneficial effect of low dose stress conditions that were applied according to the similia principle to cells previously disturbed by more severe stress conditions. In first instance, we discuss criteria for research on the similia principle at the cellular level. Then, the homologous ('isopathic') approach is reviewed, in which the initial (high dose) stress used to disturb cellular physiology and the subsequent (low dose) stress are identical. Beneficial effects of low dose stress are described in terms of increased cellular survival capacity and at the molecular level as an increase in the synthesis of heat shock proteins (hsps). Both phenomena reflect a stimulation of the endogenous cellular self-recovery capacity. Low dose stress conditions applied in a homologous approach stimulate the synthesis of hsps and enhance survival in comparison with stressed cells that were incubated in the absence of low dose stress conditions. Thirdly, the specificity of the low dose stress condition is described where the initial (high dose) stress is different in nature from the subsequently applied (low dose) stress; the heterologous or 'heteropathic' approach. The results support the similia principle at the cellular level and add to understanding of how low dose stress conditions influence the regulatory processes underlying self-recovery. In addition, the phenomenon of 'symptom aggravation' which is also observed at the cellular level, is discussed in the context of self-recovery. Finally, the difference in efficiency between the homologous and the heterologous approach is discussed; a perspective is indicated for further research; and the relationship between studies on the similia principle and the recently introduced concept of 'postconditioning hormesis' is emphasized. Copyright 2009 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

  20. Cellular therapies: Day by day, all the way.

    Science.gov (United States)

    Atilla, Erden; Kilic, Pelin; Gurman, Gunhan

    2018-04-18

    Tremendous effort and knowledge have elucidated a new era of 'cellular therapy,' also called "live" or "living" drugs. There are currently thousands of active clinical trials that are ongoing, seeking hope for incurable conditions thanks to the increased accessibility and reliability of gene editing and cellular reprogramming. Accomplishments in various adoptive T cell immunotherapies and chimeric antigen receptor (CART) T cell therapies oriented researchers to the field. Cellular therapies are believed to be the next generation of curative therapeutics in many ways, the classification and nomenclature for these applications have not yet reached a consensus. Trends in recent years are moving towards making tissues and cell processes only in centers with production permits. It is quite promising that competent authorities have increased licensing activities of tissue and cell establishments in their countries, under good practice (GxP) rules, and preclinical and clinical trials involving cell-based therapies have led to significant investments. Despite the initiatives undertaken and the large budgets that have been allocated, only limited success has been achieved in cellular therapy compared to conventional drug development. Cost, and cost effectiveness, are important issues for these novel therapies to meet unmet clinical needs, and there are still many scientific, translational, commercializational, and ethical questions that do not have answers. The main objectives of this review is to underline the current position of cellular therapies in research, highlight the timely topic of immunotherapy and chimeric antigen receptor (CAR) T-cell treatment, and compile information related to regulations and marketing of cellular therapeutic approaches worldwide. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Are cellular phone blocking applications effective for novice teen drivers?

    Science.gov (United States)

    Creaser, Janet I; Edwards, Christopher J; Morris, Nichole L; Donath, Max

    2015-09-01

    Distracted driving is a significant concern for novice teen drivers. Although cellular phone bans are applied in many jurisdictions to restrict cellular phone use, teen drivers often report making calls and texts while driving. The Minnesota Teen Driver Study incorporated cellular phone blocking functions via a software application for 182 novice teen drivers in two treatment conditions. The first condition included 92 teens who ran a driver support application on a smartphone that also blocked phone usage. The second condition included 90 teens who ran the same application with phone blocking but which also reported back to parents about monitored risky behaviors (e.g., speeding). A third control group consisting of 92 novice teen drivers had the application and phone-based software installed on the phones to record cellular phone (but not block it) use while driving. The two treatment groups made significantly fewer calls and texts per mile driven compared to the control group. The control group data also demonstrated a higher propensity to text while driving rather than making calls. Software that blocks cellular phone use (except 911) while driving can be effective at mitigating calling and texting for novice teen drivers. However, subjective data indicates that some teens were motivated to find ways around the software, as well as to use another teen's phone while driving when they were unable to use theirs. Cellular phone bans for calling and texting are the first step to changing behaviors associated with texting and driving, particularly among novice teen drivers. Blocking software has the additional potential to reduce impulsive calling and texting while driving among novice teen drivers who might logically know the risks, but for whom it is difficult to ignore calling or texting while driving. Copyright © 2015 Elsevier Ltd and National Safety Council. All rights reserved.

  2. Sub-cellular distribution and translocation of TRP channels.

    Science.gov (United States)

    Toro, Carlos A; Arias, Luis A; Brauchi, Sebastian

    2011-01-01

    Cellular electrical activity is the result of a highly complex processes that involve the activation of ion channel proteins. Ion channels make pores on cell membranes that rapidly transit between conductive and non-conductive states, allowing different ions to flow down their electrochemical gradients across cell membranes. In the case of neuronal cells, ion channel activity orchestrates action potentials traveling through axons, enabling electrical communication between cells in distant parts of the body. Somatic sensation -our ability to feel touch, temperature and noxious stimuli- require ion channels able to sense and respond to our peripheral environment. Sensory integration involves the summing of various environmental cues and their conversion into electrical signals. Members of the Transient Receptor Potential (TRP) family of ion channels have emerged as important mediators of both cellular sensing and sensory integration. The regulation of the spatial and temporal distribution of membrane receptors is recognized as an important mechanism for controlling the magnitude of the cellular response and the time scale on which cellular signaling occurs. Several studies have shown that this mechanism is also used by TRP channels to modulate cellular response and ultimately fulfill their physiological function as sensors. However, the inner-working of this mode of control for TRP channels remains poorly understood. The question of whether TRPs intrinsically regulate their own vesicular trafficking or weather the dynamic regulation of TRP channel residence on the cell surface is caused by extrinsic changes in the rates of vesicle insertion or retrieval remain open. This review will examine the evidence that sub-cellular redistribution of TRP channels plays an important role in regulating their activity and explore the mechanisms that control the trafficking of vesicles containing TRP channels.

  3. Time scale of diffusion in molecular and cellular biology

    International Nuclear Information System (INIS)

    Holcman, D; Schuss, Z

    2014-01-01

    Diffusion is the driver of critical biological processes in cellular and molecular biology. The diverse temporal scales of cellular function are determined by vastly diverse spatial scales in most biophysical processes. The latter are due, among others, to small binding sites inside or on the cell membrane or to narrow passages between large cellular compartments. The great disparity in scales is at the root of the difficulty in quantifying cell function from molecular dynamics and from simulations. The coarse-grained time scale of cellular function is determined from molecular diffusion by the mean first passage time of molecular Brownian motion to a small targets or through narrow passages. The narrow escape theory (NET) concerns this issue. The NET is ubiquitous in molecular and cellular biology and is manifested, among others, in chemical reactions, in the calculation of the effective diffusion coefficient of receptors diffusing on a neuronal cell membrane strewn with obstacles, in the quantification of the early steps of viral trafficking, in the regulation of diffusion between the mother and daughter cells during cell division, and many other cases. Brownian trajectories can represent the motion of a molecule, a protein, an ion in solution, a receptor in a cell or on its membrane, and many other biochemical processes. The small target can represent a binding site or an ionic channel, a hidden active site embedded in a complex protein structure, a receptor for a neurotransmitter on the membrane of a neuron, and so on. The mean time to attach to a receptor or activator determines diffusion fluxes that are key regulators of cell function. This review describes physical models of various subcellular microdomains, in which the NET coarse-grains the molecular scale to a higher cellular-level, thus clarifying the role of cell geometry in determining subcellular function. (topical review)

  4. Time scale of diffusion in molecular and cellular biology

    Science.gov (United States)

    Holcman, D.; Schuss, Z.

    2014-05-01

    Diffusion is the driver of critical biological processes in cellular and molecular biology. The diverse temporal scales of cellular function are determined by vastly diverse spatial scales in most biophysical processes. The latter are due, among others, to small binding sites inside or on the cell membrane or to narrow passages between large cellular compartments. The great disparity in scales is at the root of the difficulty in quantifying cell function from molecular dynamics and from simulations. The coarse-grained time scale of cellular function is determined from molecular diffusion by the mean first passage time of molecular Brownian motion to a small targets or through narrow passages. The narrow escape theory (NET) concerns this issue. The NET is ubiquitous in molecular and cellular biology and is manifested, among others, in chemical reactions, in the calculation of the effective diffusion coefficient of receptors diffusing on a neuronal cell membrane strewn with obstacles, in the quantification of the early steps of viral trafficking, in the regulation of diffusion between the mother and daughter cells during cell division, and many other cases. Brownian trajectories can represent the motion of a molecule, a protein, an ion in solution, a receptor in a cell or on its membrane, and many other biochemical processes. The small target can represent a binding site or an ionic channel, a hidden active site embedded in a complex protein structure, a receptor for a neurotransmitter on the membrane of a neuron, and so on. The mean time to attach to a receptor or activator determines diffusion fluxes that are key regulators of cell function. This review describes physical models of various subcellular microdomains, in which the NET coarse-grains the molecular scale to a higher cellular-level, thus clarifying the role of cell geometry in determining subcellular function.

  5. Cellularized Bilayer Pullulan-Gelatin Hydrogel for Skin Regeneration.

    Science.gov (United States)

    Nicholas, Mathew N; Jeschke, Marc G; Amini-Nik, Saeid

    2016-05-01

    Skin substitutes significantly reduce the morbidity and mortality of patients with burn injuries and chronic wounds. However, current skin substitutes have disadvantages related to high costs and inadequate skin regeneration due to highly inflammatory wounds. Thus, new skin substitutes are needed. By combining two polymers, pullulan, an inexpensive polysaccharide with antioxidant properties, and gelatin, a derivative of collagen with high water absorbency, we created a novel inexpensive hydrogel-named PG-1 for "pullulan-gelatin first generation hydrogel"-suitable for skin substitutes. After incorporating human fibroblasts and keratinocytes onto PG-1 using centrifugation over 5 days, we created a cellularized bilayer skin substitute. Cellularized PG-1 was compared to acellular PG-1 and no hydrogel (control) in vivo in a mouse excisional skin biopsy model using newly developed dome inserts to house the skin substitutes and prevent mouse skin contraction during wound healing. PG-1 had an average pore size of 61.69 μm with an ideal elastic modulus, swelling behavior, and biodegradability for use as a hydrogel for skin substitutes. Excellent skin cell viability, proliferation, differentiation, and morphology were visualized through live/dead assays, 5-bromo-2'-deoxyuridine proliferation assays, and confocal microscopy. Trichrome and immunohistochemical staining of excisional wounds treated with the cellularized skin substitute revealed thicker newly formed skin with a higher proportion of actively proliferating cells and incorporation of human cells compared to acellular PG-1 or control. Excisional wounds treated with acellular or cellularized hydrogels showed significantly less macrophage infiltration and increased angiogenesis 14 days post skin biopsy compared to control. These results show that PG-1 has ideal mechanical characteristics and allows ideal cellular characteristics. In vivo evidence suggests that cellularized PG-1 promotes skin regeneration and may

  6. Evaluation of cellular influences caused by calcium carbonate nanoparticles.

    Science.gov (United States)

    Horie, Masanori; Nishio, Keiko; Kato, Haruhisa; Endoh, Shigehisa; Fujita, Katsuhide; Nakamura, Ayako; Kinugasa, Shinichi; Hagihara, Yoshihisa; Yoshida, Yasukazu; Iwahashi, Hitoshi

    2014-03-05

    The cellular effects of calcium carbonate (CaCO₃) nanoparticles were evaluated. Three kinds of CaCO₃ nanoparticles were employed in our examinations. One of the types of CaCO₃ nanoparticles was highly soluble. And solubility of another type of CaCO₃ nanoparticle was lower. A stable CaCO₃ nanoparticle medium dispersion was prepared and applied to human lung carcinoma A549 cells and human keratinocyte HaCaT cells. Then, mitochondrial activity, cell membrane damage, colony formation ability, DNA injury, induction of oxidative stress, and apoptosis were evaluated. Although the influences of CaCO₃ nanoparticles on mitochondrial activity and cell membrane damage were small, "soluble" CaCO₃ nanoparticles exerted some cellular influences. Soluble CaCO₃ nanoparticles also induced a cell morphological change. Colony formation was inhibited by CaCO₃ nanoparticle exposure. In particular, soluble CaCO₃ nanoparticles completely inhibited colony formation. The influence on intracellular the reactive oxygen species (ROS) level was small. Soluble CaCO₃ nanoparticles caused an increase in C/EBP-homologous protein (CHOP) expression and the activation of caspase-3. Moreover, CaCO₃ exposure increased intracellular the Ca²⁺ level and activated calpain. These results suggest that cellular the influences of CaCO₃ nanoparticles are mainly caused by intracellular calcium release and subsequently disrupt the effect of calcium signaling. In conclusion, there is possibility that soluble CaCO₃ nanoparticles induce cellular influences such as a cell morphological change. Cellular influence of CaCO₃ nanoparticles is caused by intracellular calcium release. If inhaled CaCO₃ nanoparticles have the potential to influence cellular events. However, the effect might be not severe because calcium is omnipresent element in cell. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  7. Prospects for cellular mutational assays in human populations

    International Nuclear Information System (INIS)

    Mendelsohn, M.L.

    1984-01-01

    Practical, sensitive, and effective human cellular assays for detecting somatic and germinal mutations would have great value in environmental mutagenesis and carcinogenesis studies. Such assays would fill the void between human mutagenicity and the data that exist from short-term tests and from mutagenicity in other species. This paper discusses the following possible human cellular assays: (1) HPRT (hypoxanthine phosphoribosyltransferase) somatic cell mutation based on 6-thioguanine resistance; (2) hemoglobin somatic cell mutation assay; (3) glycophorin somatic cell mutation assay; and (4) LDH-X sperm cell mutation assay. 18 references

  8. Design of Efficient Mirror Adder in Quantum- Dot Cellular Automata

    Science.gov (United States)

    Mishra, Prashant Kumar; Chattopadhyay, Manju K.

    2018-03-01

    Lower power consumption is an essential demand for portable multimedia system using digital signal processing algorithms and architectures. Quantum dot cellular automata (QCA) is a rising nano technology for the development of high performance ultra-dense low power digital circuits. QCA based several efficient binary and decimal arithmetic circuits are implemented, however important improvements are still possible. This paper demonstrate Mirror Adder circuit design in QCA. We present comparative study of mirror adder cells designed using conventional CMOS technique and mirror adder cells designed using quantum-dot cellular automata. QCA based mirror adders are better in terms of area by order of three.

  9. Hyper bio assembler for 3D cellular systems

    CERN Document Server

    Arai, Fumihito; Yamato, Masayuki

    2015-01-01

    Hyper Bio Assembler for Cellular Systems is the first book to present a new methodology for measuring and separating target cells at high speed and constructing 3D cellular systems in vitro. This book represents a valuable resource for biologists, biophysicists and robotic engineers, as well as researchers interested in this new frontier area, offering a better understanding of the measurement, separation, assembly, analysis and synthesis of complex biological tissue, and of the medical applications of these technologies. This book is the outcome of the new academic fields of the Ministry of Education, Culture, Sports, Science and Technology’s Grant-in-Aid for Scientific Research in Japan.

  10. Cellular regulation of the structure and function of aortic valves

    Directory of Open Access Journals (Sweden)

    Ismail El-Hamamsy

    2010-01-01

    Full Text Available The aortic valve was long considered a passive structure that opens and closes in response to changes in transvalvular pressure. Recent evidence suggests that the aortic valve performs highly sophisticated functions as a result of its unique microscopic structure. These functions allow it to adapt to its hemodynamic and mechanical environment. Understanding the cellular and molecular mechanisms involved in normal valve physiology is essential to elucidate the mechanisms behind valve disease. We here review the structure and developmental biology of aortic valves; we examine the role of its cellular parts in regulating its function and describe potential pathophysiological and clinical implications.

  11. Is central dogma a global property of cellular information flow?

    Science.gov (United States)

    Piras, Vincent; Tomita, Masaru; Selvarajoo, Kumar

    2012-01-01

    The central dogma of molecular biology has come under scrutiny in recent years. Here, we reviewed high-throughput mRNA and protein expression data of Escherichia coli, Saccharomyces cerevisiae, and several mammalian cells. At both single cell and population scales, the statistical comparisons between the entire transcriptomes and proteomes show clear correlation structures. In contrast, the pair-wise correlations of single transcripts to proteins show nullity. These data suggest that the organizing structure guiding cellular processes is observed at omics-wide scale, and not at single molecule level. The central dogma, thus, globally emerges as an average integrated flow of cellular information.

  12. Prospects for cellular mutational assays in human populations

    Energy Technology Data Exchange (ETDEWEB)

    Mendelsohn, M.L.

    1984-06-29

    Practical, sensitive, and effective human cellular assays for detecting somatic and germinal mutations would have great value in environmental mutagenesis and carcinogenesis studies. Such assays would fill the void between human mutagenicity and the data that exist from short-term tests and from mutagenicity in other species. This paper discusses the following possible human cellular assays: (1) HPRT (hypoxanthine phosphoribosyltransferase) somatic cell mutation based on 6-thioguanine resistance; (2) hemoglobin somatic cell mutation assay; (3) glycophorin somatic cell mutation assay; and (4) LDH-X sperm cell mutation assay. 18 references.

  13. Lattice gas cellular automata and lattice Boltzmann models an introduction

    CERN Document Server

    Wolf-Gladrow, Dieter A

    2000-01-01

    Lattice-gas cellular automata (LGCA) and lattice Boltzmann models (LBM) are relatively new and promising methods for the numerical solution of nonlinear partial differential equations. The book provides an introduction for graduate students and researchers. Working knowledge of calculus is required and experience in PDEs and fluid dynamics is recommended. Some peculiarities of cellular automata are outlined in Chapter 2. The properties of various LGCA and special coding techniques are discussed in Chapter 3. Concepts from statistical mechanics (Chapter 4) provide the necessary theoretical background for LGCA and LBM. The properties of lattice Boltzmann models and a method for their construction are presented in Chapter 5.

  14. Is central dogma a global property of cellular information flow?

    Directory of Open Access Journals (Sweden)

    Vincent ePiras

    2012-11-01

    Full Text Available The central dogma of molecular biology has come under scrutiny in recent years. Here, we reviewed high-throughput mRNA and protein expression data of Escherichia coli, Saccharomyces cerevisiae, and several mammalian cells. At both single cell and population scales, the statistical comparisons between the entire transcriptomes and proteomes show clear correlation structures. In contrast, the pair-wise correlations of single transcript to protein show nullity. These data suggest that the organizing structure guiding cellular processes is observed at omics-wide scale and not at single molecule level. The central dogma, thus, globally emerges as an average integrated flow of cellular information.

  15. PM - processing for manufacturing of metals with cellular structures

    International Nuclear Information System (INIS)

    Strobl, S.; Danninger, H.

    2001-01-01

    In this review the major Processes about manufacturing of metals with cellular structure are described - based on powder metallurgy, chemical deposition and some other methods (without melting techniques). It can be shown that during the last decade many interesting innovations led to new production methods to design cellular materials. Some of them are used nowadays in industry. Also characterization and properties become more important and have therefore been carried out carefully, because of their strong influence on the functions and applications of such materials. (author)

  16. Reliable self-replicating machines in asynchronous cellular automata.

    Science.gov (United States)

    Lee, Jia; Adachi, Susumu; Peper, Ferdinand

    2007-01-01

    We propose a self-replicating machine that is embedded in a two-dimensional asynchronous cellular automaton with von Neumann neighborhood. The machine dynamically encodes its shape into description signals, and despite the randomness of cell updating, it is able to successfully construct copies of itself according to the description signals. Self-replication on asynchronously updated cellular automata may find application in nanocomputers, where reconfigurability is an essential property, since it allows avoidance of defective parts and simplifies programming of such computers.

  17. Nonsynchronous updating in the multiverse of cellular automata

    Science.gov (United States)

    Reia, Sandro M.; Kinouchi, Osame

    2015-04-01

    In this paper we study updating effects on cellular automata rule space. We consider a subset of 6144 order-3 automata from the space of 262144 bidimensional outer-totalistic rules. We compare synchronous to asynchronous and sequential updatings. Focusing on two automata, we discuss how update changes destroy typical structures of these rules. Besides, we show that the first-order phase transition in the multiverse of synchronous cellular automata, revealed with the use of a recently introduced control parameter, seems to be robust not only to changes in update schema but also to different initial densities.

  18. A Giant Vulvar Mass: A Case Study of Cellular Angiofibroma

    Science.gov (United States)

    Aydın, Ümit; Terzi, Hasan; Turkay, Ünal; Eruyar, Ahmet Tuğrul; Kale, Ahmet

    2016-01-01

    Cellular angiofibroma is a mesenchymal tumor that affects both genders. Nucci et al. first described it in 1997. Cellular angiofibroma is generally a small and asymptomatic mass that primarily arises in the vulvar-vaginal region, although rare cases have been reported in the pelvic and extrapelvic regions. It affects women most often during the fifth decade of life. The treatment requires simple local excision due to low local recurrence and no chance of metastasization. The current study presents a case of angiofibroma in the vulvar region that measured approximately 20 cm. PMID:27293929

  19. A Giant Vulvar Mass: A Case Study of Cellular Angiofibroma

    Directory of Open Access Journals (Sweden)

    Ümit Aydın

    2016-01-01

    Full Text Available Cellular angiofibroma is a mesenchymal tumor that affects both genders. Nucci et al. first described it in 1997. Cellular angiofibroma is generally a small and asymptomatic mass that primarily arises in the vulvar-vaginal region, although rare cases have been reported in the pelvic and extrapelvic regions. It affects women most often during the fifth decade of life. The treatment requires simple local excision due to low local recurrence and no chance of metastasization. The current study presents a case of angiofibroma in the vulvar region that measured approximately 20 cm.

  20. Pathologic Cellular Events in Smoking-Related Pancreatitis

    Energy Technology Data Exchange (ETDEWEB)

    Thrower, Edwin [Department of Internal Medicine, Section of Digestive Diseases, Yale University School of Medicine, New Haven, CT 06520 (United States); Veterans Affairs Connecticut Healthcare, West Haven, CT 06516 (United States)

    2015-04-29

    Pancreatitis, a debilitating inflammatory disorder, results from pancreatic injury. Alcohol abuse is the foremost cause, although cigarette smoking has recently surfaced as a distinct risk factor. The mechanisms by which cigarette smoke and its toxins initiate pathological cellular events leading to pancreatitis, have not been clearly defined. Although cigarette smoke is composed of more than 4000 compounds, it is mainly nicotine and the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), which have been extensively studied with respect to pancreatic diseases. This review summarizes these research findings and highlights cellular pathways which may be of relevance in initiation and progression of smoking-related pancreatitis.