NUI Maynooth Eprint Archive
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Roadmap on holography
No full textFrom its inception holography has proven an extremely productive and attractive area of research. While specific technical applications give rise to 'hot topics', and three-dimensional (3D) visualisation comes in and out of fashion, the core principals involved continue to lead to exciting innovations in a wide range of areas. We humbly submit that it is impossible, in any journal document of this type, to fully reflect current and potential activity; however, our valiant contributors have produced a series of documents that go no small way to neatly capture progress across a wide range of core activities. As editors we have attempted to spread our net wide in order to illustrate the breadth of international activity. In relation to this we believe we have been at least partially successful
The English School Reforms: Competition, Innovation and Fragmentation
No full textThe last 30 years have seen efforts by successive governments, of different political persuasions, to improve the English education system. Common to all of these reform
efforts is a concern to close the gap in attainment between students from economically disadvantaged students and their peers, although the approaches tried have varied
considerably. More recently, they have involved an increased emphasis on the idea of allowing schools greater autonomy within a policy context based on market forces
as the main improvement strategy. In this chapter, we analyse these developments in order to draw lessons for those in other countries who are interested in promoting greater equity within their national education systems. This leads us to argue that whilst school autonomy can be a positive force—particular where it encourages teachers to work together in exploring more inclusive practices—it requires coordination at the local level and the introduction of accountability arrangements that provide space for experimentation, as well as resources to promote the professional development of teachers
Challenging Silences: Democratic Citizenship Education and Historical Memory in Poland and Guatemala
No full textThis paper draws upon data from two youth-focused, ethnographically informed inquiries—one in Poland, the other in Guatemala—to describe how historical memory can conflict with both state historical narratives and with globalized approaches to democratic citizenship education. This analysis helps us to better understand the ways that, in post-conflict societies, schools function as spaces in which overlapping claims of community, nation, and world frame the development of youth citizenship and belongin
Approximate dynamic programming for stochastic resource allocation problems
No full textA stochastic resource allocation model, based on the
principles of Markov decision processes (MDPs), is proposed in this paper. In particular, a general-purpose framework is
developed, which takes into account resource requests for both instant and future needs. The considered framework can handle two types of reservations (i.e., specified and unspecified time interval reservation requests), and implement an overbooking business strategy to further increase business revenues. The resulting dynamic pricing problems can be regarded as sequential decision-making problems under uncertainty, which is solved by
means of stochastic dynamic programming (DP) based
algorithms. In this regard, Bellman’s backward principle of
optimality is exploited in order to provide all the implementation mechanisms for the proposed reservation pricing algorithm. The curse of dimensionality, as the inevitable issue of the DP both for instant resource requests and future resource reservations, occurs. In particular, an approximate dynamic programming
(ADP) technique based on linear function approximations is
applied to solve such scalability issues. Several examples are provided to show the effectiveness of the proposed approac
Tree diversity promotes growth of late successional species despite increasing deer damage in a restored forest
No full textThe role of tree diversity in restored forests and its impact on key ecological processes like growth and resistance to herbivory has become increasingly important. We analyzed height growth and white-tailed deer Odocoileus virginianus browsing damage to saplings of 16 broadleaved tree species in a large-scale (13 ha) reforestation experiment in Maryland, USA, where we manipulated tree diversity in 70 1,225-m2 plots. After four growing seasons, higher plot-level tree richness led to increased deer browsing damage (i.e., associational susceptibility). Despite increased deer damage to saplings in mixed plots, tree richness had no overall effect on sapling height growth. However, diversity–height relationships were related to species functional traits. Light demanding species with large leaves and faster growth rates had reduced heights in mixtures, whereas shade-tolerant, slower-growing species generally had either increased or unchanged height growth in diverse tree communities, likely related to increased canopy closure in mixtures relative to monocultures. We show that tree diversity can improve growth of late successional species despite exacerbated mammalian herbivore damage. By facilitating the establishment of species with a range of life-history strategies, increased tree diversity may enhance ecosystem multi-functionality in the early stages of forest restoration
Foliar water uptake by coastal wetland plants: A novel water acquisition mechanism in arid and humid subtropical mangroves
No full textClimate change alters freshwater availability in many ecosystems leading to shifts in distributions for many plants. Despite living exclusively in intertidal, saline environments, mangroves rely on non-saline water to maintain plant productivity. However, several mangrove species persist in arid environments where non-saline water from rain and groundwater sources are limited. Under these conditions, foliar water uptake from fog and mist may be an important water acquisition strategy.
We conducted a field experiment in arid Baja California Sur, Mexico along with a controlled mist chamber experiment (using seedlings sourced from humid subtropical region, Florida, USA) to show that three co-occurring, neotropical mangrove species, Avicennia germinans, Laguncularia racemosa and Rhizophora mangle, growing in both arid and humid environments can access water condensed on their leaves.
Foliar water uptake was greatest in A. germinans and lowest in R. mangle, possibly reflecting leaf traits associated with species-specific water balance strategies. In our field misting experiment, the contribution of foliar water uptake was higher in A. germinans (32 ± 2%) than L. racemosa (26 ± 2%) and R. mangle (16 ± 1%). Foliar water uptake also varied across locations for L. racemosa and R. mangle, with declining uptake towards both species’ northern range limits in Baja California Sur, suggesting the distribution patterns of arid-zone mangroves may be affected by species-specific spatial variation in foliar water use. Within species, foliar water use was comparable across field and controlled experiments irrespective of source population (Baja California Sur vs. Florida), suggesting foliar water uptake is not an arid-zone adaptation, and is instead used as a supplemental water balance strategy in arid and humid neotropical mangroves.
Synthesis. Our findings indicate mangroves have the potential to access atmospheric water, such as rain, dew and sea fog, through their leaves to offset soil water deficits. Variation in foliar water use across these three neotropical mangrove species may influence mangrove species distributions across arid-zone and pseudo-drought (highly saline) environments, with implications for mangrove response to climate change
The SCFSkp2 ubiquitin ligase complex modulates TRAIL-R2-induced apoptosis by regulating FLIP(L)
No full textTRAIL-R2 (DR5) is a clinically-relevant therapeutic target and a key target for immune effector cells. Herein, we identify a novel interaction between TRAIL-R2 and the Skp1-Cullin-1-F-box (SCF) Cullin-Ring E3 Ubiquitin Ligase complex containing Skp2 (SCFSkp2). We find that SCFSkp2 can interact with both TRAIL-R2’s pre-ligand association complex (PLAC) and ligand-activated death-inducing signalling complex (DISC). Moreover, Cullin-1 interacts with TRAIL-R2 in its active NEDDylated form. Inhibiting Cullin-1’s DISC recruitment using the NEDDylation inhibitor MLN4924 (Pevonedistat) or siRNA increased apoptosis induction in response to TRAIL. This correlated with enhanced levels of the caspase-8 regulator FLIP at the TRAIL-R2 DISC, particularly the long splice form, FLIP(L). We subsequently found that FLIP(L) (but not FLIP(S), caspase-8, nor the other core DISC component FADD) interacts with Cullin-1 and Skp2. Importantly, this interaction is enhanced when FLIP(L) is in its DISC-associated, C-terminally truncated p43-form. Prevention of FLIP(L) processing to its p43-form stabilises the protein, suggesting that by enhancing its interaction with SCFSkp2, cleavage to the p43-form is a critical step in FLIP(L) turnover. In support of this, we found that silencing any of the components of the SCFSkp2 complex inhibits FLIP ubiquitination, while overexpressing Cullin-1/Skp2 enhances its ubiquitination in a NEDDylation-dependent manner. DISC recruitment of TRAF2, previously identified as an E3 ligase for caspase-8 at the DISC, was also enhanced when Cullin-1’s recruitment was inhibited, although its interaction with Cullin-1 was found to be mediated indirectly via FLIP(L). Notably, the interaction of p43-FLIP(L) with Cullin-1 disrupts its ability to interact with FADD, caspase-8 and TRAF2. Collectively, our results suggest that processing of FLIP(L) to p43-FLIP(L) at the TRAIL-R2 DISC enhances its interaction with co-localised SCFSkp2, leading to disruption of p43-FLIP(L)’s interactions with other DISC components and promoting its ubiquitination and degradation, thereby modulating TRAIL-R2-mediated apoptosis
Functionalized magnetic nanomaterials for electrochemical biosensing of cholesterol and cholesteryl palmitate
No full textSynthesis and functionalization of magnetite nanoparticles (Fe3O4) was achieved with the view to covalently bind both cholesterol oxidase and cholesterol esterase biorecognition agents for the development of free and total cholesterol biosensors. Prior to enzyme attachment, Fe3O4 was functionalized with 3-aminopropyltriethoxysilane (APTES) and polyamidoamine (PAMAM) dendrimer. Characterization of the material was performed by FT-IR and UV spectroscopy, SEM/EDX surface analysis and electrochemical investigations. The response to cholesterol and its palmitate ester was examined using cyclic voltammetry. Optimum analytical performance for the free cholesterol biosensor was obtained using APTES-functionalized magnetite with a sensitivity of 101.9 μA mM−1 cm−2, linear range 0.1–1 mM and LOD of 80 μM when operated at 37 °C. In the case of the total cholesterol biosensor, the best analytical performance was obtained using PAMAM dendrimer-modified magnetite with sensitivity of 73.88 μA mM−1 cm−2 and linear range 0.1–1.5 mM, with LOD of 90 μM. A stability study indicated that the free cholesterol biosensors retained average activity of 98% after 25 days while the total cholesterol biosensors retained 85% activity upon storage over the same period
Synthesis, Characterization, and Biological Profiling of Ruthenium(II)-Based 4-Nitro- and 4-Amino-1,8-naphthalimide Conjugates
No full textWe report the synthesis, photophysical characterization, and biological evaluation of four DNA-binding ruthenium(II) polypyridyl 4-nitro- and 4-amino-1,8-naphthalimide conjugates. A meta arrangement around the ring connecting the 1,8-naphthalimide to a bipyridine ligand creates a cleft, the result of which renders the shape of the complex complementary to that of DNA. We have demonstrated that each complex exhibits water solubility and a distinctive set of photophysical properties that has allowed the nature of their interaction with DNA to be probed by various ground- and excited-state titrations. Furthermore, by varying the ancillary ligands, we also demonstrate their ability to act as DNA photocleavers, where all compounds have been found to cleave supercoiled DNA with high efficiency. Detailed cellular uptake experiments revealed that the conjugates accumulate in the cytoplasm and nucleus of HeLa cells, showing characteristic red metal-to-ligand charge-transfer emission, and also exhibit photoactivated cytotoxicity within the cells upon irradiation at 450 nm. A comparison between the meta and para arrangements of the 1,8-naphthalimide moiety relative to the Ru(II) center suggests increased DNA binding in the case of the meta arrangement; however, bipyridine–4-amino-1,8-naphthalimide conjugates appear to show superior phototoxicity in comparison to their 4-nitro derivatives