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Dual-task interference: Attentional and neurophysiological influences

HIRAGA, Cynthia Y.; GARRY, Michael I.; CARSON, Richard G.; SUMMERS, Jeffery J.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.49%
Performing two tasks simultaneously often degrades performance of one or both tasks. While this dual-task interference is classically interpreted in terms of shared attentional resources, where two motor tasks are performed simultaneously interactions within primary motor cortex (i.e., activity-dependent coupling) may also be a contributing factor. In the present study TMS (transcranial magnetic stimulation) was used to examine the contribution of activity-dependent coupling to dual-task interference during concurrent performance of a bimanual coordination task and a discrete probe reaction time (RT) task involving the foot. Experiments 1 and 2 revealed that activity-dependent coupling within the leg corticomotor pathway was greater during dual-task performance than single-task performance, and this was associated with interference on the probe RT task (i.e., increased RT). Experiment 3 revealed that dual-task interference occurred regardless of whether the dual-task involved two motor tasks or a motor and cognitive task, however activity-dependent coupling was present only when a dual motor task was performed. This suggests that activity-dependent coupling is less detrimental to performance than attentional processes operating upstream of the corticomotor system. Finally...

Interference of some aqueous two-phase system phase-forming components in protein determination by the Bradford method

Silverio, Sara C.; Moreira, Sergio; Milagres, Adriane Maria Ferreira; Macedo, Eugenia A.; Teixeira, Jose A.; Mussatto, Solange I.
Fonte: ACADEMIC PRESS INC ELSEVIER SCIENCE; SAN DIEGO Publicador: ACADEMIC PRESS INC ELSEVIER SCIENCE; SAN DIEGO
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.47%
The interference of some specific aqueous two-phase system (ATPS) phase-forming components in bovine serum albumin (BSA) determination by the Bradford method was investigated. For this purpose, calibration curves were obtained for BSA in the presence of different concentrations of salts and polymers. A total of 19 salts [Na2SO4, (NH4)(2)SO4, MgSO4, LiSO4, Na2HPO4, sodium phosphate buffer (pH 7.0), NaH2PO4, K2HPO4, potassium phosphate buffer (pH 7.0), KH2PO4, C6H8O7, Na3C6HSO7, KCHO2, NaCHO2, NaCO3, NaHCO3, C2H4O2, sodium acetate buffer (pH 4.5), and NaC2H3O2] and 7 polymers [PEG 4000, PEG 8000, PEG 20000, UCON 3900, Ficoll 70000, PES 100000, and PVP 40000] were tested, and each calibration curve was compared with the one obtained for BSA in water. Some concentrations of salts and polymers had considerable effect in the BSA calibration curve. Carbonate salts were responsible for the highest salt interference, whereas citric and acetic acids did not produce interference even in the maximum concentration level tested (5 wt%). Among the polymers, UCON gave the highest interference, whereas Ficoll did not produce interference when used in concentrations up to 10 wt%. It was concluded that a convenient dilution of the samples prior to the protein quantification is needed to ensure no significant interference from ATPS phase-forming constituents. (C) 2011 Elsevier Inc. All rights reserved.

Estudo experimental do efeito de interferência no escoamento ao redor de cilindros alinhados. ; Experimental investigation of flow-interference effects around circular cylinders in tandem.

Assi, Gustavo Roque da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 16/12/2005 PT
Relevância na Pesquisa
36.52%
Esta Dissertação de Mestrado apresenta um estudo experimental sobre os efeitos de interferência das vibrações induzidas pelo escoamento ao redor de cilindros rígidos livres para oscilar transversalmente ao escoamento fluido. Primeiramente, justifica a necessidade de pesquisas experimentais dentro do contexto prático da engenharia offshore, que motiva este trabalho. Apresenta uma revisão bibliográfica sobre escoamentos ao redor de corpos rombudos seguida de uma síntese sobre vibrações induzidas pelo escoamento. Destacam-se as oscilações causadas por VIV – Vibrações Induzidas por Vórtices e “galloping” como os fenômenos até o momento atribuídos às excitações de um cilindro isolado e um par de cilindros alinhados com o escoamento. Apresenta a metodologia experimental empregada, descrevendo a aplicação de bases elásticas fletoras com um grau de liberdade. Introduz as técnicas experimentais e de tratamento de sinais utilizadas e faz rápidas considerações sobre a realização de ensaios nos dois canais de água circulante onde os experimentos foram conduzidos. Os resultados apresentados, discutidos e comparados envolvem: medições da resposta dinâmica em amplitude e freqüência dominante de oscilação; medição instantânea do ângulo de fase entre a força fluida e o deslocamento do cilindro e do ângulo de fase entre as oscilações de dois cilindros; e medições da dinâmica da esteira com PIV. Os arranjos de cilindros estudados são: cilindro isolado; par alinhado com cilindro à montante oscilando; par alinhado com cilindro à jusante oscilando; e par alinhado com ambos os cilindro oscilando. Todas as configurações analisadas em detalhes possuem baixo parâmetro de massa e baixíssimo parâmetro de amortecimento . Os espaçamentos entre os centros dos cilindros alinhados variam entre . A faixa de velocidade reduzida analisada está entre. Um cilindro isolado apresentou resposta típica de VIV com os três ramos de resposta (inicial...

Análise da interferência em traduções do gênero receita realizadas por estudantes brasileiros de espanhol como língua estrangeira; Investigating interference in the translation of recipes by Brazilian students of Spanish as a foreign language

Oliveira, Bruna Macedo de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/09/2013 PT
Relevância na Pesquisa
36.44%
Neste trabalho propomos uma análise do fenômeno da interferência em traduções do gênero receita feitas por estudantes brasileiros de E/LE, com base num estudo empírico de corpus comparável, corpus paralelo e dados cognitivos. Entendendo a interferência como a incorporação de elementos de uma língua na produção em outra (MACKEY, 1970 apud PRESAS, 2000), acreditamos que a utilização de uma estrutura frequente no texto fonte, mas pouco usual na língua meta, constitui um resultado indesejável/não natural (TAGNIN, 2005), especialmente no caso de textos que se pretendem comunicativos, como é o caso da receita. A partir de dados empíricos, o estudo buscou verificar a hipótese de Presas (2000), segundo a qual é possível encontrar na tradução um tipo de interferência que, ao contrário do fenômeno normalmente descrito nos estudos de aquisição/aprendizagem, atuaria na direção oposta, ou seja, da língua estrangeira sobre a língua materna. De acordo com nossa suposição inicial, certas estruturas poderiam favorecer a incidência desse fenômeno, exatamente por apresentarem um funcionamento análogo, mas não idêntico, nas duas línguas. Com o propósito de investigar essa hipótese, coletamos um corpus de traduções para o português de uma receita em espanhol...

Determinação de fatores de interferência de produtos de fissão do urânio na Análise por Ativação Neutrônica; Determination of uranium fission products interference factors in Neutron Activation Analysis

Ribeiro Junior, Iberê Souza
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 24/06/2014 PT
Relevância na Pesquisa
36.44%
A análise por ativação com nêutrons é um método utilizado na determinação de diversos elementos em diferentes tipos de matrizes. Entretanto, quando a amostra contém altos teores de U ocorre o problema de interferência devido aos produtos de fissão do isótopo 235U. Um dos métodos de tratar este problema é fazer a correção usando fatores de interferência devido à fissão do U para os radionuclídeos utilizados nas análises dos elementos. No presente estudo foram determinados os valores dos fatores de interferência devido à fissão do U para os radioisótopos 141Ce, 143Ce,140La, 99Mo, 147Nd, 153Sm e 95Zr no reator nuclear de pesquisas IEA-R1 do IPEN-CNEN/SP. Esses fatores de interferência foram determinados experimentalmente, por meio da irradiação dos padrões sintéticos em uma determinada posição do reator, e teoricamente, determinando a razão dos fluxos de nêutrons epitérmicos e térmicos na mesma posição onde os padrões sintéticos foram irradiados e utilizando parâmetros nucleares da literatura. Os fatores de interferência obtidos foram comparados com os valores reportados em outros estudos. Para avaliar esses fatores de interferência, eles foram aplicados em análises dos elementos alvo deste estudo...

Interference of some ATPS phase-forming components in protein determination by the Bradford method

Silvério, Sara C.; Moreira, Sérgio; Milagres, Adriane M. F.; Macedo, Eugénia A.; Teixeira, J. A.; Mussatto, Solange I.
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Publicado em //2012 ENG
Relevância na Pesquisa
36.47%
The interference of some specific aqueous two-phase system (ATPS) phase-forming components in bovine serum albumin (BSA) determination by the Bradford method was investigated. For this purpose, calibration curves were obtained for BSA in the presence of different concentrations of salts and polymers. A total of 19 salts [Na(2)SO(4), (NH(4))(2)SO(4), MgSO(4), LiSO(4), Na(2)HPO(4), sodium phosphate buffer (pH 7.0), NaH(2)PO(4), K(2)HPO(4), potassium phosphate buffer (pH 7.0), KH(2)PO(4), C(6)H(8)O(7), Na(3)C(6)H(5)O(7), KCHO(2), NaCHO(2), NaCO(3), NaHCO(3), C(2)H(4)O(2), sodium acetate buffer (pH 4.5), and NaC(2)H(3)O(2)] and 7 polymers [PEG 4000, PEG 8000, PEG 20000, UCON 3900, Ficoll 70000, PES 100000, and PVP 40000] were tested, and each calibration curve was compared with the one obtained for BSA in water. Some concentrations of salts and polymers had considerable effect in the BSA calibration curve. Carbonate salts were responsible for the highest salt interference, whereas citric and acetic acids did not produce interference even in the maximum concentration level tested (5wt%). Among the polymers, UCON gave the highest interference, whereas Ficoll did not produce interference when used in concentrations up to 10wt%. It was concluded that a convenient dilution of the samples prior to the protein quantification is needed to ensure no significant interference from ATPS phase-forming constituents. Copyright © 2011 Elsevier Inc. All rights reserved.

Frequency shift based multiple access interference canceller for DS-CDMA systems

Gonçalves, Luís; Silva, Adão; Gameiro, Atílio
Fonte: IEEE Publicador: IEEE
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
36.44%
The cyclostationary properties of Direct Sequence Spread Spectrum signals are well known. These cyclostationary properties imply a redundancy between frequency components separated by multiples of the symbol rate. In this paper we present a Multiple Access Interference Canceller that explores this property and applies to UMTS-TDD. This frequency domain Canceller acts in the spreaded signal in such way that minimizes the interference and noise at its output (Minimum Mean Squared Error Criterium). The performance is evaluated in two detector configurations: one including the Frequency Shift Canceller (FSC) and the other plus a Parallel Interference Canceller (PIC). The results are benchmarked against the performance of the conventional RAKE detector and the conventional PIC detector.; PRAXIS XXI; FCT; ASILUM project; VISEF project

Electromagnetic interference reduction by dynamic impedance balancing applied to biosensors

Negrão,João Francisco Ribeiro; Araujo,Guilherme Augusto Limeira; Costa Júnior,Carlos Tavares da; Souza,Daniel Cardoso de
Fonte: SBEB - Sociedade Brasileira de Engenharia Biomédica Publicador: SBEB - Sociedade Brasileira de Engenharia Biomédica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2013 EN
Relevância na Pesquisa
36.44%
INTRODUCTION: Electromagnetic interference caused by electric power lines adversely affects the signals of electronic instruments, especially those with low amplitude levels. This type of interference is known as common-mode interference. There are many methods and architectures used to minimize the influence of this kind of interference on electronic instruments, the most common of which is the use of band-reject filters. This paper presents the analysis, development, prototype and test of a new reconfigurable filter architecture for biomedical instruments, aiming to reduce the common-mode interference and preserve the useful signal components in the same frequency range as that of the noise, using the technique of dynamic impedance balancing. METHODS: The circuit blocks were mathematically modeled and the overall closed-loop transfer function was derived. Then the project was described and simulated in the VHDL_AMS language and also in an electronics simulation software, using discrete component blocks, with and without feedback. After theoretical analysis and simulation results, a prototype circuit was built and tested using as input a signal obtained from ECG electrodes. RESULTS: The results from the experimental circuit matched those from simulation: a 97.6% noise reduction was obtained in simulations using a sinusoidal signal...

Semantic Interference In A Delayed Naming Task: Evidence for the Response Exclusion Hypothesis

Mahon, Bradford Z.; Janssen, Niels; Schirm, Walter; Caramazza, Alfonso
Fonte: American Psychological Association Publicador: American Psychological Association
EN_US
Relevância na Pesquisa
36.44%
In 2 experiments participants named pictures of common objects with superimposed distractor words. In one naming condition, the pictures and words were presented simultaneously on every trial, and participants produced the target response immediately. In the other naming condition, the presentation of the picture preceded the presentation of the distractor by 1,000 ms, and participants delayed production of their naming response until distractor word presentation. Within each naming condition, the distractor words were either semantic category coordinates of the target pictures or unrelated. Orthogonal to this manipulation of semantic relatedness, the frequency of the pictures’ names was manipulated. The authors observed semantic interference effects in both the immediate and delayed naming conditions but a frequency effect only in the immediate naming condition. These data indicate that semantic interference can be observed when target picture naming latencies do not reflect the bottleneck at the level of lexical selection. In the context of other findings from the picture–word interference paradigm, the authors interpret these data as supporting the view that the semantic interference effect arises at a postlexical level of processing.; Psychology

Interference competition between introduced black rats and endemic Galápagos rice rats; Interference competition between introduced black rats and endemic Galapagos rice rats

Harris, D.; Macdonald, D.
Fonte: Ecological Soc Amer Publicador: Ecological Soc Amer
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
36.47%
Replicated field experiments were used to quantify and to describe the mechanism of competition between the introduced black rat Rattus rattus and the endemic Santiago rice rat Nesoryzomys swarthi on Santiago Island, Galápagos Islands, Ecuador. The removal of R. rattus significantly slowed the rate of seasonal population decline in N. swarthi. This effect was particularly evident for female, relative to male, N. swarthi and appeared to be driven solely by enhanced immigration; no other fitness or space use parameters were affected. The candidate hypotheses to explain the mechanism of competition were exploitation competition, interference by resource defense, and interference by aggressive encounter. To distinguish between hypotheses, we conducted a replicated resource supplementation experiment with patchy food, scattered food, and no food (control) treatments. The opportunistic R. rattus responded to the extra resources with increased adult immigration and juvenile recruitment, resulting in a significant abundance boost of sevenfold on patchy grids and fourfold on scattered grids. Females increased in body mass, and the breeding season was lengthened. In contrast, there was no change in the abundance of N. swarthi and no obvious benefit to reproduction. Instead...

The Mechanisms of Proactive Interference and Their Relationship with Working Memory

Glaser, Yi
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
36.44%
Working memory (WM) capacity – the capacity to maintain and manipulate information in mind – plays an essential role in high-level cognitive functions. An important determinant of WM capacity is the ability to resolve interference of previously encoded but no longer relevant information (proactive interference: PI). Four different mechanisms of PI resolution involving binding and inhibition have been proposed in the literature, although debate continues regarding their role. Braver et al. (2007) introduced an important distinction in the PI resolution literature, proposing two general types of PI control mechanisms that occur at different time points: proactive control (involves preparation in advance of the interference) and reactive control (occurs after interference occurs). This thesis proposed that among these four functions involving binding and inhibition, item inhibition and binding could be involved in proactive control, while familiarity inhibition and episodic inhibition could be involved in reactive control. The question is which mechanism in each pair is indeed involved in proactive control and reactive control respectively, and how these proactive control and reactive control mechanisms work together to resolve PI. In addition...

LTE uplink MIMO receiver with low complexity interference cancellation

Yin, Bei; Cavallaro, Joseph R.
Fonte: Sprnger Publicador: Sprnger
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.49%
In LTE/LTE-A uplink receiver, frequency domain equalizers (FDE) are adopted to achieve good performance. However, in multi-tap channels, the residual inter-symbol and inter-antenna interference still exist after FDE and degrade the performance. Conventional interference cancellation schemes can minimize this interference by using frequency domain interference cancellation. However, those schemes have high complexity and large feedback latency, especially when adopting a large number of iterations. These result in low throughput and require a large amount of resource in software defined radio implementation. In this paper, we propose a novel low complexity interference cancellation scheme to minimize the residual interference in LTE/LTE-A uplink. Our proposed scheme can bring about 2 dB gains in different channels, but only adds up to 7.2 % complexity to the receiver. The scheme is further implemented on Xilinx FPGA. Compared to other conventional interference cancellation schemes, our scheme has less complexity, less data to store, and shorter feedback latency.

All cumulative semantic interference is not equal: A test of the Dark Side Model of lexical access

Walker Hughes, Julie
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
36.51%
Language production depends upon the context in which words are named. Renaming previous items results in facilitation while naming pictures semantically related to previous items causes interference. A computational model (Oppenheim, Dell, & Schwartz, 2010) proposes that both facilitation and interference are the result of using naming events as “learning experiences” to ensure future accuracy. The model successfully simulates naming data from different semantic interference paradigms by implementing a learning mechanism that creates interference and a boosting mechanism that resolves interference. This study tested this model’s assumptions that semantic interference effects in naming are created by learning and resolved by boosting. Findings revealed no relationship between individual performance across semantic interference tasks, and measured learning and boosting abilities did not predict performance. These results suggest that learning and boosting mechanisms do not fully characterize the processes underlying semantic interference when naming.

Performance analysis of a JTIDS/link-16-type waveform transmitted over slow, flat Nakagami fading channels in the presence of narrowband interference

Kao, Chi-Han
Fonte: Monterey, California. Naval Postgraduate School, 2008. Publicador: Monterey, California. Naval Postgraduate School, 2008.
Formato: xxiv, 182 p. ; 28 cm.
Relevância na Pesquisa
36.47%
Link-16 is a tactical data link currently employed by the United States Navy, the Joint Services, and forces of North Atlantic Treaty Organization. It provides presumably secure and jam-resistant tactical information for land, sea, and air platforms. The communication terminal of Link-16 is called Joint Tactical Information Distribution System (JTIDS) and features Reed-Solomon (RS) coding, symbol interleaving, cyclic code-shift keying (CCSK) for M-ary symbol modulation, minimum-shift keying for chip modulation, and combined frequency-hopping and direct sequence spread spectrum for transmission security. In this dissertation, we investigate the performance of a JTIDS/Link-16-type waveform in both additive white Gaussian noise (AWGN) and narrowband interference when the signal is transmitted over a slow, flat Nakagami fading channel. In general, the results show that barrage noise interference has the most effect in degrading JTIDS's performance when signal-to-interference ratio (SIR) is small, whereas pulsed-noise interference for a smaller fraction of time that the interference is on causes the greatest degradation when SIR is large, whether the channel is fading or not. In addition, two modified JTIDS/Link-16-compatible systems are proposed and evaluated. The first system uses errors-and-erasures decoding (EED) in place of errorsonly RS decoding...

Item noise versus context noise: using the list length effect to investigate the source of interference in recognition memory.

Kinnell, Angela
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2009
Relevância na Pesquisa
36.51%
The present thesis aimed to investigate the source of interference in recognition memory. There are two primary alternatives – the item noise approach, in which interference comes about as a consequence of the other items on the study list, and the context noise approach, wherein interference arises from the previous contexts in which an item has been encountered. Alternatively, interference may occur through a combination of both item and context noise. There are many mathematical models designed to simulate the recognition process that incorporate either item or context noise, or both. Item noise models predict a significant list length effect, that is, that memory for an item that was part of a short list at study is better than that for an item that was part of a long list. Context noise models no not predict a significant difference in memory based on the length of the study list. The presence or absence of the list length effect can therefore be used as a mechanism by which to differentiate item and context noise models. The list length effect is among the most documented and replicated findings in the recognition memory literature (Gronlund & Elam, 1994). Yet, while many experiments have been conducted which have identified a significant list length effect in recognition (e.g. Bowles & Glanzer...

THE USE OF PULSE INTERFERENCE TESTS FOR THE DETERMINATION OF SPECIFIC YIELD IN FRACTURED ROCK SETTINGS

ELMHIRST, LAURA
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.47%
An analytical model is presented for the analysis of pulse interference tests conducted in a fractured porous medium with connection to a free surface boundary at the water table. The solution is applicable to open borehole pulse interference tests due to the accommodation of multiple horizontal fractures intersecting each wellbore and a connection from the uppermost horizontal fracture to a free surface boundary. The solution is derived using the Laplace transform method and evaluation of the solution is performed by numerical inversion using the Talbot algorithm. Based on an informal sensitivity analysis, unique values for transmissivity, storativity, specific storage, vertical hydraulic conductivity and specific yield are predicted over a range of realistic values for these parameters. The analytical model is used to analyze slug tests and pulse interference tests conducted in a fractured gneiss formation. The results of these tests are compared to long-term pumping tests to identify the effect of measurement scale on transmissivity, storativity, vertical hydraulic conductivity and specific yield obtained in a fractured rock setting. Scale artefacts relating to measurement or analysis methods are minimized through the use of consistent well configurations in each of the applied hydraulic testing methods. The geometric mean estimates of transmissivity and storativity are shown to vary by less than an order of magnitude from local-scale tests to long-term pumping tests. The geometric mean specific yield result from a series of pulse interference tests that samples both highly fractured and poorly fractured portions of the rock formation approximates the long-term pumping test estimate of specific yield. The geometric mean result for vertical hydraulic conductivity decreases by approximately 1.5 orders of magnitude from the slug test to pumping test scale; however...

Source-Channel Coding Techniques in the Presence of Interference and Noise

ABOU SALEH, AHMAD
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.52%
As wireless systems proliferate worldwide, interference is becoming one of the main problems for system designers. Interference, which occurs when multiple transmissions take place over a common communication medium, limits system performance. Wireless devices can coordinate the use of scarce radio resources in order to manage the interference and establish successful communication. To effectively deal with the interference problem, some wireless devices must have a certain level of knowledge about the interference. In practice, this knowledge comes at the expense of using more resources (such as employing a proper channel training mechanism). With the remaining available resources, the question is how to achieve reliable communication? This thesis investigates an information theoretic approach and employs several coding techniques to improve system performance by either cancelling the interference or extracting knowledge from it about the information signal. The first part of this thesis considers the transmission of information signals over a fading channel that is disturbed with additional interference. The system's information theoretic limit in terms of mean square error distortion is assessed. Moreover, hybrid coding schemes are proposed and analyzed to obtain an achievable performance. As an extension to this problem...

Interference considerations in MIMO-based cellular systems

Jiang, Chenzi
Fonte: University of Delaware Publicador: University of Delaware
Tipo: Tese de Doutorado
Relevância na Pesquisa
36.52%
Cimini, Leonard; In this thesis, we consider MIMO-based intra-tier interference in single-tier cellular systems, and inter-tier interference in two-tier femtocellular systems. In single-tier cellular systems, intra-tier interference is a major limiting factor on performance. To mitigate this intra-tier interference, a scheduling algorithm is developed in the presence of an uncertain interference environment. Due to the limited knowledge about the interference, a "margin" is applied in estimating the transmission rate, that is, a backoff from the achievable rate in the previous packet transmission. This algorithm is overly conservative; so, the performance is not satisfying, especially in channels where the fading is relatively uncorrelated from packet to packet. It is diffcult to obtain good performance without knowledge of the interference. For two-tier femtocelular systems, the introduction of femtocells into existing macrocellular systems has the potential to significantly improve the coverage and capacity of these networks. However, the inter-tier interference caused to macrocellular users due to femtocellular transmissions is also a big challenge. In this thesis, the efficacy of applying beamforming (BF) with nulling at the femtocellular base stations (FBSs) is studied in order to mitigate the interference to macrocellular users. The performance of other transmission modes...

Dominant-negative interference with defence signalling by truncation mutations of the tomato Cf-9 disease resistance genes

Barker, Claire; Baillie, Brett; Hammond-Kosack, Kim E; Jones, Jonathan D G; Jones, David
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.51%
The tomato Cf-9 gene confers resistance to races of the leaf mould fungus Cladosporium fulvum that carry the Avr9 avirulence gene. Cf-9 was isolated by transposon tagging using a modified maize Dissociation (Ds) element. This generated an allelic series of Ds-induced mutations of Cf-9, of which two were found to confer novel phenotypes in a screen for mutants affecting wild-type Cf-9 function in trans. Genetic and molecular analysis of these mutants suggested semidominant, Avr9-dependent, negative-interfering mutations involving Ds insertions in a defined subregion of Cf-9. Interference was associated with expression of the 5′-end of Cf-9 upstream of the Ds insertions in these mutants, suggesting that truncated Cf-9 proteins were the likely cause of interference. Transgenic tomato lines harbouring Cf-9 constructs with premature stop codons in positions similar to the Ds insertions also showed interference, indicating that the presence of Ds was not required for interference to occur. Interestingly, interference in these transgenic lines was completely dominant and was associated with a pronounced developmental phenotype that was dependent on co-expression of Cf-9, Avr9 and a truncated Cf-9 transgene. However, interference with a weakly autoactive Hcr9 gene was Avr9-independent and did not cause a developmental phenotype...

Interference between work and nonwork roles: the development of a new South African instrument

Koekemoer,Eileen; Mostert,Karina; Rothmann Jr,Ian
Fonte: SA Journal of Industrial Psychology Publicador: SA Journal of Industrial Psychology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
36.47%
ORIENTATION: The interference between work and personal life is a central issue in the 21st century as employees attempt to balance or integrate their involvement in multiple social roles. RESEARCH PURPOSE: The purpose of this study was to, (1) develop new items for a more comprehensive work-nonwork interference instrument, (2) evaluate the newly developed items to retain those items that accurately capture the different dimensions and (3) eliminate undesirable items from the different subscales in the instrument. MOTIVATION FOR THE STUDY: Although the interaction between work and personal life has received extensive attention in the work-family fields of research, various theoretical, empirical and measurement issues need to be addressed. RESEARCH DESIGN, APPROACH AND METHOD: A cross-sectional survey design was used to collect the data. MAIN FINDINGS: Initially, 89 items were developed. During the pilot study among mineworkers (n = 245), 41 poor items were eliminated on the basis of descriptive statistics, inter-item correlations, item-total correlations and the qualitative investigation of items highly redundant in terms of wording. Thereafter, the instrument (48 items) was administered to 366 support and academic personnel at a tertiary institution. Using Rasch analyses and item correlations...