Contemporaneous fluctuations in T cell responses to persistent herpes virus infections

The classical paradigm for T cell dynamics suggests that the resolution of a primary acute virus infection is followed by the generation of a long-lived pool of memory T cells that is thought to be highly stable. Very limited alteration in this repertoire is expected until the immune system is re-challenged by reactivation of latent viruses or by cross-reactive pathogens. Contradicting this view, we show here that the T cell repertoire specific for two different latent herpes viruses in the peripheral blood displayed significant contemporaneous co-fluctuations of virus-specific CD8(+) T cells. The coordinated responses to two different viruses suggest that the fluctuations within the T cell repertoire may be driven by sub-clinical viral reactivation or a more generalized 'bystander' effect. The later contention was supported by the observation that, while absolute number of CD3(+) T cells and their subsets and also the cell surface phenotype of antigen-specific T cells remained relatively constant, a loss of CD62L expression in the total CD8(+) T cell population was coincident with the expansion of tetramer-positive virus-specific T cells. This study demonstrates that the dynamic process of T cell expansion and contractions in persistent viral infections is not limited to the acute phase of infection, but also continues during the latent phase of infection.

Perceptions of the intergroup structure and anti-Asian prejudice among white Australians

Subjective intergroup beliefs and authoritarianism were assessed in a field study (N=255) of White Australians' anti-Asian stereotyping and prejudice. A social identity analysis of intergroup prejudice was adopted, such that perceptions of the intergroup structure (instability, permeability, legitimacy and higher ingroup status) were proposed as predictors of higher prejudice (blatant and covert) and less favorable stereotyping. Consistent with the social identity approach, both independent and interacting roles for sociostructural predictors of Anti-Asian bias were observed, even after demographic and personality variables were controlled. For example, perceived legitimacy was associated with higher prejudice when White Australians' status position relative to Asian Australians was valued. Moreover, when participants evaluated Whites' position as unstable and high status or legitimate, perceptions of permeable intergroup boundaries were associated with anti-Asian bias. The present findings demonstrate status protection responses in advantaged group members in a field setting, lending weight to the contention that perceptions of sociostructural threat interact to predict outgroup derogation. Implications for theories of intergroup relations are discussed.

Cytochrome P450-mediated metabolism of haloperidol and reduced haloperidol to pyridinium metabolites

Haloperidol ( HP) has been reported to undergo cytochrome P450 (P450)-mediated metabolism to potentially neurotoxic pyridinium metabolites; however, the chemical pathways and specific enzymes involved in these reactions remain to be identified. The aims of the current study were to (i) fully identify the cytochrome P450 enzymes capable of metabolizing HP to the pyridinium metabolite, 4-(4-chlorophenyl)- 1-(4-fluorophenyl)-4-oxobutylpyridinium (HPP+), and reduced HP (RHP) to 4-(4-chlorophenyl)- 1-(4-fluorophenyl)-4-hydroxybutylpyridinium (RHPP+); and (ii) determine whether 4-(4-chlorophenyl)- 1-(4-fluorophenyl)-4-oxobutyl-1,2,3,6-tetrahydropyridine (HPTP) and 4-(4-chlorophenyl)1-( 4-fluorophenyl)-4-hydroxybutyl-1,2,3,6-tetrahydropyridine (RHPTP) were metabolic intermediates in these pathways. In vitro studies were conducted using human liver microsomal preparations and recombinant human cytochrome P450 enzymes (P450s 1A1, 1A2, 1B1, 2A6, 2B6, 2C9, 2C19 2D6, 2E1, 3A4, 3A5, and 3A7) expressed in bicistronic format with human NADPH cytochrome P450 reductase in Escherichia coli membranes. Pyridinium formation from HP and RHP was highly correlated across liver preparations, suggesting the same enzyme or enzymes were responsible for both reactions. Cytochrome P450s 3A4, 3A5, and 3A7 were the only recombinant enzymes which demonstrated significant catalytic activity under optimized conditions, although trace levels of activity could be catalyzed by NADPHP450 reductase alone. NADPH-P450 reductase-mediated activity was inhibited by reduced glutathione but not catalase or superoxide dismutase, suggesting O-2-dependent oxidation. No evidence was obtained to support the contention that HPTP and RHPTP are intermediates in these pathways. K-m values for HPP+ (34 +/- 5 mu M) and RHPP+ (64 +/- 4 mu M) formation by recombinant P450 3A4 agreed well with those obtained with human liver microsomes, consistent with P450 3A4 being the major catalyst of pyridinium metabolite formation in human liver.

Play behaviours and play object preferences of young children with autistic disorder in a clinical play environment

Play is the primary occupation of childhood and provides a potentially powerful means of assessing and treating children with autistic disorder. This study utilized a cross-sectional comparison design to investigate the nature of play engagement in children with AD (n = 24), relative to typically developing children (n = 34) matched for chronological age. Play behaviours were recorded in a clinical play environment. Videotapes comprising 15 minutes of the children's spontaneous play behaviour were analysed using time-interval analysis. The particular play behaviours observed and play objects used were coded. Differences in play behaviours (p < 0.0001) and play object preferences (p < 0.0001) were identified between the groups. Findings regarding play behaviour contribute to contention in the literature surrounding functional and symbolic play. Explanations for play object preferences are postulated. Recommendations are made regarding clinical application of findings in terms of enhancing assessment and intervention by augmenting motivation.

Generative acts: Family and community involvement of older Australians

The article adopts a developmental approach to successful human aging by exploring the concept of generativity in relation to a study of older Australians' lived experiences of involvement in the family and community. Qualitative data, collected through focus group interviews, were analyzed interpretively using recent developments in Erikson's theory of generativity as a framework. As a result, the present study contributes an in-depth understanding of the role of generative acts to the lives of older people. The data provide illustrative support for Erikson's contention of a generativity/stagnation crisis in later life. Involvement in the family and community is seen as a productive and generative activity, which promotes a positive experience of aging. Two further emergent themes are also explored. First, the experiences of study participants illustrate the reciprocal and cyclical nature of grand-generativity, and the importance of intergenerational relationships. Finally, the data contribute to our knowledge of cultural generativity, and in particular the passing on of cultural knowledge through narratives and modeling.

Strong electronic correlations in superconducting organic charge transfer salts

We review the role of strong electronic correlations in quasi-two-dimensional organic charge transfer salts such as (BEDT-TTF)(2)X, (BETS)(2)Y, and beta'-[Pd(dmit)(2)](2)Z. We begin by defining minimal models for these materials. It is necessary to identify two classes of material: the first class is strongly dimerized and is described by a half-filled Hubbard model; the second class is not strongly dimerized and is described by a quarter-filled extended Hubbard model. We argue that these models capture the essential physics of these materials. We explore the phase diagram of the half-filled quasi-two-dimensional organic charge transfer salts, focusing on the metallic and superconducting phases. We review work showing that the metallic phase, which has both Fermi liquid and 'bad metal' regimes, is described both quantitatively and qualitatively by dynamical mean field theory (DMFT). The phenomenology of the superconducting state is still a matter of contention. We critically review the experimental situation, focusing on the key experimental results that may distinguish between rival theories of superconductivity, particularly probes of the pairing symmetry and measurements of the superfluid stiffness. We then discuss some strongly correlated theories of superconductivity, in particular the resonating valence bond (RVB) theory of superconductivity. We conclude by discussing some of the major challenges currently facing the field. These include parameterizing minimal models, the evidence for a pseudogap from nuclear magnetic resonance (NMR) experiments, superconductors with low critical temperatures and extremely small superfluid stiffnesses, the possible spin- liquid states in kappa-(ET)(2)Cu-2(CN)(3) and beta'-[Pd(dmit)(2)](2)Z, and the need for high quality large single crystals.

Performance analysis of multi-radio AODV in hybrid wireless mesh networks

Wireless Mesh Networks (WMNs), based on commodity hardware, present a promising technology for a wide range of applications due to their self-configuring and self-healing capabilities, as well as their low equipment and deployment costs. One of the key challenges that WMN technology faces is the limited capacity and scalability due to co-channel interference, which is typical for multi-hop wireless networks. A simple and relatively low-cost approach to address this problem is the use of multiple wireless network interfaces (radios) per node. Operating the radios on distinct orthogonal channels permits effective use of the frequency spectrum, thereby, reducing interference and contention. In this paper, we evaluate the performance of the multi-radio Ad-hoc On-demand Distance Vector (AODV) routing protocol with a specific focus on hybrid WMNs. Our simulation results show that under high mobility and traffic load conditions, multi-radio AODV offers superior performance as compared to its single-radio counterpart. We believe that multi-radio AODV is a promising candidate for WMNs, which need to service a large number of mobile clients with low latency and high bandwidth requirements.

Heritage language loss and the implications for ethnic identity maintenance over time

Language has been seen as a central pillar to ethnic identity. When the possibility of heritage language loss becomes imminent, therefore, concern turns towards the consequences for feelings of ethnic group membership. Heritage language researchers have indicated that the heritage language is so strongly associated with the individual���s cultural background that heritage language loss could have negative implications for the sense of identity to the ethnic group. This study investigates the relationship between language and ethnic identity over time among Gaelic learners in Nova Scotia. In order to identify the specific processes of heritage language use, the Gaelic learners are compared to French (second language), learners living in the same English-speaking milieu. Path analyses reveal that, only among Gaelic learners, there is an initial separation of language and ethnic identity, but that, over time, ethnic identity is a direct outcome of language use. The results support Edwards��� (1985), contention, at least in the case of heritage languages, that language and identity are not always strongly linked. It is suggested that this may be especially true in contexts where there is little opportunity for contact with members of the heritage language group.

AVALIA����O POR MEIO DE MODELOS DE GESSO DAS ALTERA����ES DENTOESQUEL��TICAS, PROMOVIDAS PELA EXPANS��O R��PIDA DA MAXILA ASSISTIDA CIRURGICAMENTE (ERMAC)

Este estudo avaliou as altera����es produzidas nos arcos dentais superiores de pacientes submetidos �� Expans��o R��pida da Maxila Assistida Cirurgicamente (ERMAC). A amostra utilizada foi composta de 50 modelos de gesso superiores de 18 pacientes, sendo seis do sexo masculino e 12 do sexo feminino, com m��dia de idade de 23,3 anos. Para cada paciente foram preparados tr��s modelos de gesso obtidos em diferentes fases: Inicial, antes do procedimento operat��rio (T1); tr��s meses p��s-expans��o (travamento do expansor) e momento da remo����o do aparelho expansor tipo Hyrax e coloca����o da placa remov��vel de acr��lico para conten����o (T2); seis meses p��s-expans��o e momento de remo����o da placa de acr��lico (T3). O dispositivo expansor utilizado foi o disjuntor tipo Hyrax. O procedimento cir��rgico adotado foi a osteotomia lateral da maxila sem o envolvimento da l��mina pterig��ide, osteotomia da espinha nasal �� linha m��dia dental (incisivos centrais superiores), separa����o da sutura palatina mediana por meio de cinzel e separa����o do septo nasal. O in��cio da ativa����o ocorreu no terceiro dia p��s-operat��rio, sendo �� de volta pela manh�� e �� �� noite, sendo que as ativa����es seguiram crit��rios cl��nicos para o controle da expans��o. As medidas foram realizadas por meio da m��quina de medi����o tridimensional (SAC), baseando-se nas altera����es nos tr��s planos (vertical, sagital e transversal) que ocorreram nos modelos de gesso. Concluiu-se que: 1. Houve um aumento estatisticamente significante nas dist��ncias transversais em todos os grupos de dentes (de incisivos centrais at�� segundos molares) de T1 para T2, demonstrando a efetividade do tratamento. De T2 para T3 n��o houve diferen��a estatisticamente significante para nenhuma vari��vel, indicando, assim, estabilidade ap��s seis meses do t��rmino da ERMAC; 2. Houve um aumento estatisticamente significante nas inclina����es dos primeiros e segundos molares dos lados direito e esquerdo e dos segundos pr��-molares apenas do lado esquerdo, sugerindo um comportamento assim��trico dos dentes avaliados; 3. Houve um aumento na largura palatina nos intervalos analisados, com diferen��as estatisticamente significantes entre T1 x T2 e T1 x T3; 4. N��o foram observadas diferen��as estatisticamente significantes na profundidade palatina nos intervalos analisados.(AU)

AVALIA����O POR MEIO DE MODELOS VIRTUAIS TRIDIMENSIONAIS DAS DIST��NCIAS INTERCANINOS E INTERMOLARES INFERIORES EM TR��S MOMENTOS

O prop��sito desse estudo foi de avaliar a estabilidade do tratamento ortod��ntico em tr��s momentos distintos, por meio de mensura����o das dist��ncias intercaninos e intermolares inferiores, utilizando, como ferramenta, modelos virtuais tridimensionais. Foram selecionados modelos de gesso da arcada inferior de 19 pacientes em tr��s fases distintas: pr��-tratamento (T1), p��s-tratamento (T2) e m��nimo de 5 anos p��s-conten����o (T3), totalizando 57 modelos, os quais foram digitalizados por meio do Scanner 3D SCANTEH ST500 (SCAN technology A/S, Dinamarca), para obten����o dos modelos virtuais tridimensionais. Nesses modelos virtuais tridimensionais foram selecionadas e mensuradas as dist��ncias entre as pontas de c��spide dos caninos, denominada dist��ncia intercaninos e pontas de c��spide mesiovestibulares dos primeiros molares, denominada dist��ncia intermolares, com o aux��lio do programa Rapidform ( Inus Technology Inc,). Para a an��lise estat��stica, foi realizada a an��lise de vari��ncia de medidas repetidas, e realizadas compara����es m��ltiplas de Bonferroni ao n��vel de signific��ncia de 5%. As dist��ncias intercaninos e intermolares, em m��dia, diminu��ram entre T1-T2 e continuaram diminuindo entre T2- T3. Ap��s 4 semanas, 20% da amostra foi novamente mensurada para avalia����o do erro do m��todo, onde foram encontrados valores m��dios semelhantes aos encontrados na primeira mensura����o. Nesse trabalho, utilizando-se modelos virtuais tridimensionais, nota-se que n��o h�� estabilidade durante e ap��s o tratamento ortod��ntico, no tocante ��s dist��ncias intercaninos e intermolares.

Audit fees, non-audit fees and auditor going-concern reporting decisions in the United Kingdom

The accounting profession has come under increased scrutiny over recent years about the growing number of non-audit fees received from audit clients and the possible negative impact of such fees on auditor independence. The argument advanced is that providing substantial amounts of non-audit services to clients may make it more likely that auditors concede to the wishes of the client management when difficult judgments are made. Such concerns are particularly salient in the case of reporting decisions related to going-concern uncertainties for financially stressed clients. This study empirically examines audit reports provided to financially stressed companies in the United Kingdom and the magnitude of audit and non-audit service fees paid to the company���s auditors. We find that the magnitude of both audit fees and non-audit fees are significantly associated with the issuance of a going-concern modified audit opinion. In particular, financially stressed companies with high audit fees are more likely to receive a going-concern modified audit opinion, whereas companies with high non-audit fees are less likely to receive a goingconcern modified audit opinion. Additional analyses indicate that the results are generally robust across alternative model and variable specifications. Overall, evidence supports the contention that high non-audit fees have a detrimental effect on going-concern reporting judgments for financially stressed U.K. companies.

The virtual pedagogy initiative

Contemporary Higher Education Institutions must adapt to address government funded calls for expansion and widened participation. The adoption of e-learning strategies, such as the use of the podcasts, can facilitate flexible learning around the needs and expectations of students. In this article we outline a number of e-learning developments at Aston University collectively referred to as the Virtual Pedagogy Initiative. Each of the strands, podcasts, vodcasts, mobile telephony and the campus wide remote broadcasts, are described pedagogically as well as technically. Where possible data highlighting the student response and experience are included. The article begins with the contention that contemporary undergraduates may be qualitatively different and can considered ���digital natives?.

Location and network effects on innovation success:evidence for UK, German and Irish manufacturing plants

Recent developments in the new economic geography and the literature on regional innovation systems have emphasised the potentially important role of networking and the characteristics of firms' local operating environment in shaping their innovative activity. Modeling UK, German and Irish plants' investments in R&D, technology transfer and networking, and their effect on the extent and success of plants' innovation activities, casts some doubt on the importance of both of these relationships. In particular, our analysis provides no support for the contention that firms or plants in the UK, Ireland or Germany with more strongly developed external links (collaborative networks or technology transfer) develop greater innovation intensity. However, although inter-firm links also have no effect on the commercial success of plants' innovation activity, intra-group links are important in terms of achieving commercial success. We also find evidence that R&D, technology transfer and networking inputs are substitutes rather than complements in the innovation process, and that there are systematic sectoral and regional influences in the efficiency with which such inputs are translated into innovation outputs. �� 2001 Elsevier Science B.V.

Efficiency improvements to the Groupe Special Mobile (GSM) digital mobile radio system

Groupe Sp��cial Mobile (GSM) has been developed as the pan-European second generation of digital mobile systems. GSM operates in the 900 MHz frequency band and employs digital technology instead of the analogue technology of its predecessors. Digital technology enables the GSM system to operate in much smaller zones in comparison with the analogue systems. The GSM system will offer greater roaming facilities to its subscribers, extended throughout the countries that have installed the system. The GSM system could be seen as a further enhancement to European integration. GSM has adopted a contention-based protocol for multipoint-to-point transmission. In particular, the slotted-ALOHA medium access protocol is used to coordinate the transmission of the channel request messages between the scattered mobile stations. Collision still happens when more than one mobile station having the same random reference number attempts to transmit on the same time-slot. In this research, a modified version of this protocol has been developed in order to reduce the number of collisions and hence increase the random access channel throughput compared to the existing protocol. The performance evaluation of the protocol has been carried out using simulation methods. Due to the growing demand for mobile radio telephony as well as for data services, optimal usage of the scarce availability radio spectrum is becoming increasingly important. In this research, a protocol has been developed whereby the number of transmitted information packets over the GSM system is increased without any additional increase of the allocated radio spectrum. Simulation results are presented to show the improvements achieved by the proposed protocol. Cellular mobile radio networks commonly respond to an increase in the service demand by using smaller coverage areas. As a result, the volume of the signalling exchanges increases. In this research, a proposal for interconnecting the various entitles of the mobile radio network over the future broadband networks based on the IEEE 802.6 Metropolitan Area Network (MAN) is outlined. Simulation results are presented to show the benefits achieved by interconnecting these entities over the broadband Networks.

Packet voice/data in local broadcast networks

A local area network that can support both voice and data packets offers economic advantages due to the use of only a single network for both types of traffic, greater flexibility to changing user demands, and it also enables efficient use to be made of the transmission capacity. The latter aspect is very important in local broadcast networks where the capacity is a scarce resource, for example mobile radio. This research has examined two types of local broadcast network, these being the Ethernet-type bus local area network and a mobile radio network with a central base station. With such contention networks, medium access control (MAC) protocols are required to gain access to the channel. MAC protocols must provide efficient scheduling on the channel between the distributed population of stations who want to transmit. No access scheme can exceed the performance of a single server queue, due to the spatial distribution of the stations. Stations cannot in general form a queue without using part of the channel capacity to exchange protocol information. In this research, several medium access protocols have been examined and developed in order to increase the channel throughput compared to existing protocols. However, the established performance measures of average packet time delay and throughput cannot adequately characterise protocol performance for packet voice. Rather, the percentage of bits delivered within a given time bound becomes the relevant performance measure. Performance evaluation of the protocols has been examined using discrete event simulation and in some cases also by mathematical modelling. All the protocols use either implicit or explicit reservation schemes, with their efficiency dependent on the fact that many voice packets are generated periodically within a talkspurt. Two of the protocols are based on the existing 'Reservation Virtual Time CSMA/CD' protocol, which forms a distributed queue through implicit reservations. This protocol has been improved firstly by utilising two channels, a packet transmission channel and a packet contention channel. Packet contention is then performed in parallel with a packet transmission to increase throughput. The second protocol uses variable length packets to reduce the contention time between transmissions on a single channel. A third protocol developed, is based on contention for explicit reservations. Once a station has achieved a reservation, it maintains this effective queue position for the remainder of the talkspurt and transmits after it has sensed the transmission from the preceeding station within the queue. In the mobile radio environment, adaptions to the protocols were necessary in order that their operation was robust to signal fading. This was achieved through centralised control at a base station, unlike the local area network versions where the control was distributed at the stations. The results show an improvement in throughput compared to some previous protocols. Further work includes subjective testing to validate the protocols' effectiveness.