Expression of a second receptor rescues self-specific T cells from thymic deletion and allows activation of autoreactive effector function.

Allelic exclusion at the T-cell receptor alpha chain locus is incomplete resulting in the generation of T cells that express two T-cell receptors. The potential involvement of such T cells in autoimmunity has been suggested [Padovan, E., Casorati, G., Dellabona, P., Meyer, S., Brockhaus, M. & Lanzavecchia, A. (1993) Science 262, 422-424; Heath, W. R. & Miller, J. F. A. P. (1993) J. Exp. Med. 178, 1807-1811]. Here we show that expression of a second T-cell receptor can rescue T cells with autospecific receptors from thymic deletion and allow their exit into the periphery. Dual receptor T cells, created by constitutive expression of two transgenic T-cell receptors on a Rag1-/- background, are tolerant to self by maintaining low levels of autospecific receptor, but selfreactive effector function (killing) can be induced through activation via the second receptor. This opens the possibility that T cells carrying two receptors in the periphery of normal individuals contain putatively autoreactive cells that could engage in autoimmune effector functions after recognition of an unrelated environmental antigen.

Generation of mice with a 200-kb amyloid precursor protein gene deletion by Cre recombinase-mediated site-specific recombination in embryonic stem cells.

Gene disruptions and deletions of up to 20kb have been generated by homologous recombination with appropriate targeting vectors in murine embryonic stem (ES) cells. Because we could not obtain a deletion of about 200 kb in the mouse amyloid precursor protein gene by the classical technique, we employed strategies involving the insertion of loxP sites upstream and downstream of the region to be deleted by homologous recombination and elicited excision of the loxP-flanked region by introduction of a Cre expression vector into the ES cells. In the first approach, the loxP sequences were inserted in two successive steps and after each step, ES cell clones were isolated and characterized. Deletion of the loxP-flanked sequence was accomplished by introducing the cre gene in a third step. In the second approach, ES cells containing the upstream loxP cassette were electroporated simultaneously with the downstream loxP targeting vector and the Cre expression plasmid. ES cells were obtained that gave rise to chimeric mice capable of germ-line transmission of the deleted amyloid precursor protein allele.

Effective Performance Evaluations For Generation X and Generation Y Employees

This Capstone focuses on the overview of generic performance evaluation process, characteristics of Generation X and Y employees in a workplace, first and second-hand research in the area of Effective Performance Evaluations for Generation X and Y employees, and recommends different approaches to performance evaluations for Generation X and Y employees to increase its effectiveness.

Socialising Around Media (SAM): Dynamic Social and Media Content Syndication for Second Screen

Today's generation of Internet devices has changed how users are interacting with media, from passive and unidirectional users to proactive and interactive. Users can use these devices to comment or rate a TV show and search for related information regarding characters, facts or personalities. This phenomenon is known as second screen. This paper describes SAM, an EU-funded research project that focuses on developing an advanced digital media delivery platform based on second screen interaction and content syndication within a social media context, providing open and standardised ways of characterising, discovering and syndicating digital assets. This work provides an overview of the project and its main objectives, focusing on the NLP challenges to be faced and the technologies developed so far.

The EU regime on biofuels in transport: Still in search of sustainability. Egmont Paper No. 68, July 2014

Like other regions of the world, the EU is developing biofuels in the transport sector to reduce oil consumption and mitigate climate change. To promote them, it has adopted favourable legislation since the 2000s. In 2009 it even decided to oblige each Member State to ensure that by 2020 the share of energy coming from renewable sources reached at least 10% of their final consumption of energy in the transport sector. Biofuels are considered the main instrument to reach that percentage since the development of other alternatives (such as hydrogen and electricity) will take much longer than expected. Meanwhile, these various legislative initiatives have driven the production and consumption of biofuels in the EU. Biofuels accounted for 4.7% of EU transport fuel consumption in 2011. They have also led to trade and investment in biofuels on a global scale. This large-scale expansion of biofuels has, however, revealed numerous negative impacts. These stem from the fact that first-generation biofuels (i.e., those produced from food crops), of which the most important types are biodiesel and bioethanol, are used almost exclusively to meet the EU’s renewable 10% target in transport. Their negative impacts are: socioeconomic (food price rises), legal (land-grabbing), environmental (for instance, water stress and water pollution; soil erosion; reduction of biodiversity), climatic (direct and indirect land-use effects resulting in more greenhouse gas emissions) and public finance issues (subsidies and tax relief). The extent of such negative impacts depends on how biofuel feedstocks are produced and processed, the scale of production, and in particular, how they influence direct land use change (DLUC) and indirect land use change (ILUC) and the international trade. These negative impacts have thus provoked mounting debates in recent years, with a particular focus on ILUC. They have forced the EU to re-examine how it deals with biofuels and submit amendments to update its legislation. So far, the EU legislation foresees that only sustainable biofuels (produced in the EU or imported) can be used to meet the 10% target and receive public support; and to that end, mandatory sustainability criteria have been defined. Yet they have a huge flaw. Their measurement of greenhouse gas savings from biofuels does not take into account greenhouse gas emissions resulting from ILUC, which represent a major problem. The Energy Council of June 2014 agreed to set a limit on the extent to which firstgeneration biofuels can count towards the 10% target. But this limit appears to be less stringent than the ones made previously by the European Commission and the European Parliament. It also agreed to introduce incentives for the use of advanced (second- and third-generation) biofuels which would be allowed to count double towards the 10% target. But this again appears extremely modest by comparison with what was previously proposed. Finally, the approach chosen to take into account the greenhouse gas emissions due to ILUC appears more than cautious. The Energy Council agreed that the European Commission will carry out a reporting of ILUC emissions by using provisional estimated factors. A review clause will permit the later adjustment of these ILUC factors. With such legislative orientations made by the Energy Council, one cannot consider yet that there is a major shift in the EU biofuels policy. Bolder changes would have probably meant risking the collapse of the high-emission conventional biodiesel industry which currently makes up the majority of Europe’s biofuel production. The interests of EU farmers would have also been affected. There is nevertheless a tension between these legislative orientations and the new Commission’s proposals beyond 2020. In any case, many uncertainties remain on this issue. As long as solutions have not been found to minimize the important collateral damages provoked by the first generation biofuels, more scientific studies and caution are needed. Meanwhile, it would be wise to improve alternative paths towards a sustainable transport sector, i.e., stringent emission and energy standards for all vehicles, better public transport systems, automobiles that run on renewable energy other than biofuels, or other alternatives beyond the present imagination.

Deterministic generation of tailored-optical-coherent-state superpositions

Pulsed coherent excitation of a two-level atom strongly coupled to a resonant cavity mode will create a superposition of two coherent states of opposite amplitudes in the field. By choosing proper parameters of interaction time and pulse shape the field after the pulse will be almost disentangled from the atom and can be efficiently outcoupled through cavity decay. The fidelity of the generation approaches unity if the atom-field coupling strength is much larger than the atomic and cavity decay rates. This implies a strong difference between even and odd output photon number counts. Alternatively, the coherence of the two generated field components can be proven by phase-dependent annihilation of the generated nonclassical superposition state by a second pulse.

Modern environmental improvement pathways for the coal power generation industry in Australia

In this work we assess the pathways for environmental improvement by the coal utilization industry for power generation in Australia. In terms of resources, our findings show that coal is a long term resource of concern as coal reserves are likely to last for the next 500 years or more. However, our analysis indicates that evaporation losses of water in power generation will approach 1000 Gl (gigalitres) per year, equivalent to a consumption of half of the Australian residential population. As Australia is the second driest continent on earth, water consumption by power generators is a resource of immediate concern with regards to sustainability. We also show that coal will continue to play a major role in energy generation in Australia and, hence, there is a need to employ new technologies that can minimize environmental impacts. The major technologies to reduce impacts to air, water and soils are addressed. Of major interest, there is a major potential for developing sequestration processes in Australia, in particular by enhanced coal bed methane (ECBM) recovery at the Bowen Basin, South Sydney Basin and Gunnedah Basin. Having said that, CO2 capture technologies require further development to support any sequestration processes in order to comply with the Kyoto Protocol. Current power generation cycles are thermodynamic limited, with 35-40% efficiencies. To move to a high efficiency cycle, it is required to change technologies of which integrated gasification combined cycle plus fuel cell is the most promising, with efficiencies expected to reach 60-65%. However, risks of moving towards an unproven technology means that power generators are likely to continue to use pulverized fuel technologies, aiming at incremental efficiency improvements (business as usual). As a big picture pathway, power generators are likely to play an increasing role in regional development; in particular EcoParks and reclaiming saline water for treatment as pressures to access fresh water supplies will significantly increase.

Physical and MAC layer techniques for next generation satellite communications

In this thesis, we consider four different scenarios of interest in modern satellite communications. For each scenario, we will propose the use of advanced solutions aimed at increasing the spectral efficiency of the communication links. First, we will investigate the optimization of the current standard for digital video broadcasting. We will increase the symbol rate of the signal and determine the optimal signal bandwidth. We will apply the time packing technique and propose a specifically design constellation. We will then compare some receiver architectures with different performance and complexity. The second scenario still addresses broadcast transmissions, but in a network composed of two satellites. We will compare three alternative transceiver strategies, namely, signals completely overlapped in frequency, frequency division multiplexing, and the Alamouti space-time block code, and, for each technique, we will derive theoretical results on the achievable rates. We will also evaluate the performance of said techniques in three different channel models. The third scenario deals with the application of multiuser detection in multibeam satellite systems. We will analyze a case in which the users are near the edge of the coverage area and, hence, they experience a high level of interference from adjacent cells. Also in this case, three different approaches will be compared. A classical approach in which each beam carries information for a user, a cooperative solution based on time division multiplexing, and the Alamouti scheme. The information theoretical analysis will be followed by the study of practical coded schemes. We will show that the theoretical bounds can be approached by a properly designed code or bit mapping. Finally, we will consider an Earth observation scenario, in which data is generated on the satellite and then transmitted to the ground. We will study two channel models, taking into account one or two transmit antennas, and apply techniques such as time and frequency packing, signal predistortion, multiuser detection and the Alamouti scheme.

Optical autocorrelator that uses a surface-emitting second-harmonic generator on (211)B GaAs

An optical autocorrelator grown on a (211)B GaAs substrate that uses visible surface-emitted second-harmonic generation is demonstrated. The (211)B orientation needs TE mode excitation only, thus eliminating the problem of the beating between the TE and TM modes that is required for (100)-grown devices; it also has the advantage of giving higher upconversion efficiency than (111) growth. Values of waveguide loss and the difference in the effective refractive index between the TE(0) and TE(1) modes were also obtained from the autocorrelation experiment.

Generation of triangular pulses in normally dispersive fibre

In this scheme, nonlinearity and dispersion in the NDF lead to various reshaping processes of an initial, conventional pulse according to the chirping value and power level at the input of the fibre. In particular, we have observed that triangular-shaped pulses can be generated for sufficiently high energies and a positive initial chirp parameter. In our experiments, 2.8 ps-FWHM, transform-limited pulses generated from a mode-locked fibre laser source at a repetition rate of 1.25 GHz were pre-chirped by propagating the pulses through different lengths of standard mono-mode fibre. The chirped pulses were then amplified to different power levels before being launched into a 2.3 km section of True Wave fibre (TWF). The corresponding numerically calculated pulse temporal intensity profile and numerical and experimental second-harmonic generation frequency-resolved optical gating (SHG FROG) spectrograms were also derived. In conclusion, we have presented numerical modelling results which show the system design parameters required for the generation of triangular-shaped pulses in a nonlinear NDF, and experimentally demonstrated triangular pulse shaping in conventional NDF.

Minority influence and argument generation

The theories of Moscovici (1980) and Nemeth (1986) concerning the cognitive processes underlying minority influence are examined in an argument generation paradigm. While Moscovici (1980) argues that minority influence increases the generation of arguments for and against the minority position, Nemeth (1986) proposes that minorities induce divergent thinking which leads to the generation of a wider range of arguments which are more original. In the first study, subjects read a minority text and then generated arguments concerning the minority issue within a specified time. The second study was similar to the first and included a condition where minority influence followed partial sensory deprivation (being placed in a dark, soundproof room for 45 minutes) which was predicted to decrease cognitive effort. Contrary to Moscovici, in neither study was there evidence that a minority led to more arguments being generated compared to a control condition (no influence). However, in one study, a minority led to more arguments being generated in the minority than in the majority direction. However, as predicted by Nemeth, in both studies a minority resulted in a wider range of arguments being generated than those proposed in the minority's message and these were rated by independent judges as being more original. Finally, as predicted, partial sensory deprivation led to a narrower range of arguments which were focused more upon issues raised in the minority text.

Optical autocorrelator that uses a surface-emitting second-harmonic generator on (211)B GaAs

An optical autocorrelator grown on a (211)B GaAs substrate that uses visible surface-emitted second-harmonic generation is demonstrated. The (211)B orientation needs TE mode excitation only, thus eliminating the problem of the beating between the TE and TM modes that is required for (100)-grown devices; it also has the advantage of giving higher upconversion efficiency than (111) growth. Values of waveguide loss and the difference in the effective refractive index between the TE(0) and TE(1) modes were also obtained from the autocorrelation experiment.

Generation of orange light from a PPKTP waveguide end-pumped by a quantum-dot tuneable laser

Here we present a compact all-room-temperature frequency-doubling scheme generating orange light, using a PPKTP waveguide and a quantum-dot external cavity diode laser (QD-ECDL). The maximum output power for the second harmonic generated light (SHG) was 1.43 mW at 613 nm, achieved for 70 mW of launched pump power at 1226 nm. This represents an important step towards a compact and wall-plug-efficient coherent orange light source, operating at room temperature.

Orange light generation from a PPKTP waveguide end pumped by a cw quantum-dot tunable laser diode

A compact all-room-temperature frequency-doubling scheme generating cw orange light with a periodically poled potassium titanyl phosphate waveguide and a quantum-dot external cavity diode laser is demonstrated. A frequency-doubled power of up to 4.3 mW at the wavelength of 612.9 nm with a conversion efficiency exceeding 10% is reported. Second harmonic wavelength tuning between 612.9 nm and 616.3 nm by changing the temperature of the crystal is also demonstrated. © Springer-Verlag 2010.

Intracavity generation of 610nm light by periodically poled near-stoichiometric lithium tantalate

Intracavity frequency doubling of an optically pumped GaInNAs semiconductor disk laser by a periodically poled near-stoichiometric lithium tantalate crystal has been investigated. Stable second-harmonic generation at 610nm has been achieved with an output power of 730mW, limited only by the spectral acceptance range and Fresnel losses of the crystal. Spectral tuning of 8nm was realised with a Fabry-Pérot etalon. © The Institution of Engineering and Technology.