187 research outputs found
Transparency isn't spoon-feeding : how a transformative approach to the use of explicit assessment criteria can support student self-regulation
No full textIf little care is taken when establishing clear assessment requirements, there is the potential for spoon-feeding. However, in this conceptual article we argue that transparency in assessment is essential to providing equality of opportunity and promoting students’ self-regulatory capacity. We begin by showing how a research-informed inclusive pedagogy, the EAT Framework, can be used to improve assessment practices to ensure that the purposes, processes, and requirements of assessment are clear and explicit to students. The EAT Framework foregrounds how students’ and teachers’ conceptions of learning (i.e., whether one has a transactional or transformative conception of learning within a specific context) impact assessment practices. In this article, we highlight the importance of being explicit in promoting access to learning, and in referencing the EAT Framework, the importance of developing transformative rather than transactional approaches to being explicit. Firstly, we discuss how transparency in the assessment process could lead to “criteria compliance” (Torrance, 2007, p. 282) and learner instrumentalism if a transactional approach to transparency, involving high external regulation, is used. Importantly, we highlight how explicit assessment criteria can hinder learner autonomy if paired with an overreliance on criteria-focused ‘coaching’ from teachers. We then address how ‘being explicit with assessment’ does not constitute spoon-feeding when used to promote understanding of assessment practices, and the application of deeper approaches to learning as an integral component of an inclusive learning environment. We then provide evidence on how explicit assessment criteria allow students to selfassess as part of self-regulation, noting that explicit criteria may be more effective when drawing on a transformative approach to transparency, which acknowledges the importance of transparent and mutual student-teacher communications about assessment requirements. We conclude by providing recommendations to teachers and students about how explicit assessment criteria can be used to improve students’ learning. Through an emphasis on transparency of process, clarity of roles, and explication of what constitutes quality within a specific discipline, underpinned by a transformative approach, students and teachers
Characteristics of HIV-1 specific T cell responses in healthy, HIV-1 negative vaccine recipients
No full textIt is estimated that there are currently 42 million individuals living today with human immunodeficiency virus-l (HIV-1) infection. Highly active anti-retroviral therapy (HAART) is the only treatment available to date, which reduces viral load and delays progression to acquired immunodeficiency syndrome (AIDS), but adherance can be a challenge due to side effects caused by drug toxicity, its cost if medication. is not free, and the complicated regimen involved (Akileswaran, Lurie et al. 2005). Resistant mutant strains evolve after long term therapy (Vaclavikova, Weber et al. 2005). These expensive drugs are not available for social and economic reasons to 80% of infected individuals in . the developing world (UNAIDS 2004). A vaccine to this virus will probably be the most effective method of stemming the pandemic (McMichael and Hanke 2002). Correlates of protection to induce sterilizing .immunity against HIV infection, or to control viral replication and prevent transmission· during chronic infection are as yet, unknown. However an association has been observed between long term non progression to disease, and the presence of functional HIV specific T cell responses. A novel Clade A HIV-l vaccine was designed to elicit T cell responses, delivered as pTH.HIVA or MVA.HIVA and has been trialled in HIV negative humans over the last 5 years. Results of the most recent clinical trials are presented, using sensitive T cell assays optimised in this study. The longevity, functional and phenotypic properties of HIV specific T cells generated by vaccination were examined. The most immunogenic vaccine regimen was observed using a pTH.HIVA DNA prime, followed by a pox virus vectored boost. mvA specific memory T cells that produced IFN-y as measured in a cultured ELISPOT, were detectable in 50% of individuals who had received vaccine up to 3 Yz years previously. These cells expanded in culture and produced anti-viral cytokines and chemokines. Through understanding the quality of vaccine induced populations of cells with regards to potential antiviral function, we may progress towards designing a HIV vaccine and immunisation schedule that will be efficacious in stemming the global pandemic.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Harnessing the learning potential of feedback: Dedicated improvement and reflection time (DIRT) in classroom practice
No full textUltra-broadband all-OPCPA petawatt facility fully based on LBO
No full textA petawatt facility fully based on noncollinear optical parametric chirped pulse amplification (NOPCPA) technology, Vulcan OPPEL (Vulcan OPCPA PEtawatt Laser), is presented. This system will be coupled with the existing hybrid-CPA/OPCPA VULCAN laser system (500 J, 500 fs beamline; 250 J, ns regime beamline) based on Nd:glass amplification. Its pulse duration (20 times shorter) combined with the system design will allow the auxiliary beamline and its secondary sources to be used as probe beams for longer pulses and their interactions with targets. The newly designed system will be mainly dedicated to electron beam generation, but could also be used to perform a variety of particle acceleration and optical radiation detection experimental campaigns. In this communication, we present the entire beamline design discussing the technology choices and the design supported by extensive simulations for each system section. Finally, we present experimental results and details of our commissioned NOPCPA picosecond front end, delivering 1.5 mJ, ∼180 nm (1/e2) of bandwidth compressed to sub-15 fs. </p
Comparison of HIV-1 specific T cell immunity in the female genital tract and blood of HIV-infected women : impact of in vitro T cell expansion on HIV-specific T cell specificity, maturational status and functional complexity
No full textIncludes bibliographical references (leaves 161-184).This study shows that HIV-specific cervical T cells can be isolated by cytobrushing and in vitro polyclonal expansion is a useful approach to increase the number of T cells available from mucosal sites. Dynal beads (1:1) in the presence of IL-2, IL-7 and IL-15 resulted in the best yields of cervical T cells while anti-CD3 in the presence of IL-2 best conserved the ex vivo T cell profile. Expanded T cell lines, irrespective of expansion method used, generally maintain their cytokine response profile to HIV anti- gens. This study shows that HIV Gag-specific blood and cervical T cells were largely mono-functional with polyfunctional T cells being detected in women with high blood CD4 count and low plasma viral load. This study confirms that HIV-specific Gag T cell responses detected in the polyclonal expanded female genital tract T cells are associated with those measured in blood during HIV infection
Effect of defocusing on picosecond laser-coupling into gold cones
No full textThis work was supported in part by DTRA under Basic Research Award No. HDTRA1-10-10077.Here, we show that defocusing of the laser in the interaction of a picosecond duration, 1.053 μm wavelength, high energy pulse with a cone-wire target does not significantly affect the laser energy coupling efficiency, but does result in a drop in the fast electron effective temperature. This may be beneficial for fast ignition, since not only were more electrons with lower energies seen in the experiment but also the lower prepulse intensity will reduce the amount of preplasma present on arrival of the main pulse, reducing the distance the hot electrons have to travel. We used the Vulcan Petawatt Laser at the Rutherford Appleton Laboratory and gold cone targets with approximately 1 mm long, 40 μm diameter copper wires attached to their tip. Diagnostics included a quartz crystal imager, a pair of highly oriented pyrolytic graphite crystal spectrometers and a calibrated CCD operating in the single photon counting regime, all of which looked at the copper Kα emission from the wire. A short pulse optical probe, delayed 400 ps relative to the main pulse was employed to diagnose the extent of plasma expansion around the wire. A ray-tracing code modeled the change in intensity on the interior surface of the cone with laser defocusing. Using a model for the wire copper Kα emission coupled to a hybrid Vlasov-Fokker-Planck code, we ran a series of simulations, holding the total energy in electrons constant whilst varying the electron temperature, which support the experimental conclusions.Peer reviewe
Increased detection of proliferating, polyfunctional, HIV-1-specific T cells in DNA-modified vaccinia virus Ankara-vaccinated human volunteers by cultured IFN-gamma ELISPOT assay.
No full textInduction of a long-term immunological memory, which can expand and defend the host upon pathogen encounter, is the "holy grail" of vaccinology. Here, using a sensitive cultured IFN-gamma ELISPOT assay, we show that 50% (15 out of 30) of healthy, HIV-1/2-uninfected volunteers who received pTHr.HIVA DNA prime-modified vaccinia virus Ankara. HIVA boost vaccine regimen 1 to 3 1/2 years ago had detectable HIV-1-specific T-cell responses. These T cells, predominantly of the CD4(+) subtype, could proliferate and produce multiple cytokines in response to in vitro peptide stimulation. Peptide mapping studies showed that the vaccine-induced CD4(+) T cells were mostly directed toward epitopes targeted in HIV-1-infected individuals. In addition, we used the same assay to re-evaluate 51 volunteers from past vaccine trial IAVI-006 and corrected the previously reported 10% of vaccine responders to 50%. Thus, we confirmed that cultured assays are a valuable tool for studying T-cell memory. These results are discussed in the context of the current state-of-affairs of the HIV-1 vaccine field
Broad TCR usage in functional HIV-1-specific CD8+ T cell expansions driven by vaccination during highly active antiretroviral therapy.
No full textDuring chronic HIV-1 infection, continuing viral replication is associated with impaired proliferative capacity of virus-specific CD8+ T cells and with the expansion and persistence of oligoclonal T cell populations. TCR usage may significantly influence CD8+ T cell-mediated control of AIDS viruses; however, the potential to modulate the repertoire of functional virus-specific T cells by immunotherapy has not been explored. To investigate this, we analyzed the TCR Vbeta usage of CD8+ T cells populations which were expanded following vaccination with modified vaccinia virus Ankara expressing a HIV-1 gag/multiepitope immunogen (MVA.HIVA) in HIV-1-infected patients receiving highly active antiretroviral therapy. Vaccinations induced the re-expansion of HIV-1-specific CD8+ T cells and these showed broad TCR Vbeta usage which was maintained for at least 1 year in some individuals. By contrast, virus-specific CD8+ T cell populations in the same donors which failed to expand after vaccination and in unvaccinated controls were oligoclonal. Simultaneously, we observed that CD8+ T cells recognizing vaccine-derived HIV-1 epitopes displayed enhanced capacity to proliferate and to inhibit HIV-1 replication in vitro, following MVA.HIVA immunizations. Taken together, these data indicate that an attenuated viral-vectored vaccine can modulate adaptive CD8+ T cell responses to HIV-1 and improve their antiviral functional capacity. The potential therapeutic benefit of this vaccination approach warrants further investigation
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