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Polychromatic pyramid wavefront sensor with MKID technology for high contrast imaging
Get PDFThe high sensitivity of the pyramid wavefront sensor has made it the preferred sensor in high contrast adaptive optics systems. Future higher contrast systems, like the Extremely Large Telescope’s Planetary Camera System, will require higher performance wavefront sensing. A further performance improvement could be achieved with a polychromatic pyramid wavefront sensor by using additional information over a broader wavelength range. The development of such systems is becoming more feasible with the emergence of new detector technologies such as microwave kinetic inductance detector arrays. These are arrays of superconductor detectors that give a position, arrival time, and measure of the energy for each incident photon. This paper introduces the polychromatic pyramid wavefront sensor concept by defining the technologies and techniques employed and their requirements. A method is developed to track the optical gains, taking advantage of the additional wavelength information, and used to compensate for optical gains within an optimized reconstructor to minimize noise propagation. An overview of expected performance improvement, using end-to-end simulations, is provided using the Keck II adaptive optics system as a reference design. The polychromatic pyramid wavefront sensor was shown to increase the limiting magnitude by 1 to 2 magnitudes, and the contrast by factors of 1.5 to 4, versus single band pyramid wavefront sensors, by sensing over a wavelength range approximately five to ten times broader (800–1800 nm) compared to Z band (152 nm wide) and H band (300 nm wide). Practical design and implementation issues have also been considered
Last Resort as a Justification for Compulsory Nasogastric Tube Feeding of Adults with Anorexia Nervosa
No full textNasogastric tube feeding may be imposed on adults with anorexia nervosa without their consent. Although it can preserve life, it can also cause significant and lasting distress, and it is widely accepted that the intervention should be employed only as a last resort. However, the concept of last resort remains insufficiently defined. Clinical guidance and case law in England and Wales use the term to guide decision making, but the thresholds by which a particular action can be considered a last resort are varied and ambiguous. Informed by human rights principles, this article articulates the relevant thresholds for last resort decisions relevant to detention, restraint and high-risk or speculative treatments, clarifying operative meanings by way of a typology
Compiler-supported reduced precision and AoS-SoA transformations for heterogeneous hardware
No full textThis study evaluates AoS-to-SoA transformations over reduced-precision data layouts for a particle simulation code on several GPU platforms: We hypothesize that SoA fits particularly well to SIMT, while AoS is the preferred storage format for many Lagrangian codes. Reduced-precision (below IEEE accuracy) is an established tool to address bandwidth constraints, although it remains unclear whether AoS and precision conversions should execute on a CPU or be deployed to a GPU if the compute kernel itself must run on an accelerator. On modern superchips where CPUs and GPUs share (logically) one data space, it is also unclear whether it is advantageous to stream data to the accelerator prior to the calculation,or whether we should let the accelerator transform data on demand, i.e.work in-place logically. We therefore introduce compiler annotations to facilitate such conversions and to give the programmer the option to orchestrate the conversions in combination with GPU offloading. For some of our compute kernels of interest, Nvidia's G200 platforms yield a speedup of around 2.6 while AMD's MI300A exhibits more robust performance yet profits less. We assume that our compiler-based techniques are applicable to a wide variety of Lagrangian codes and beyond
Decarbonising Heating with Power-Hydrogen Optimisation
No full textThis paper presents an analysis of an integrated power-hydrogen system for an energy community, incorporating renewable energy sources as solar panels, battery storage, and grid interaction. This study focuses on optimising energy consumption and minimising CO2 emissions. Genetic algorithm techniques are implemented to find the optimal values for various parameters in the system such as battery usage and grid utilisation. The analysis considers power and heating loads, with renewable energy sources meeting the power load and surplus energy used to produce hydrogen. The findings highlight the potential of integrated power-to-hydrogen systems for decarbonising small communities
Modelling the impact of quasar redshift errors on the full-shape analysis of correlations in the Lyman-α forest
No full textIn preparation for the first cosmological measurements from the full shape of the Lyman- (Ly ) forest from Dark Energy Spectroscopic Instrument (DESI), we must carefully model all relevant systematics that might bias our analysis. It has been shown that random quasar redshift errors produce a smoothing effect on the mean quasar continuum in the Ly forest region. This, in turn, gives rise to spurious features in the Ly autocorrelation and its cross-correlation with quasars. Using synthetic data sets based on the DESI survey, we confirm that the impact on baryon acoustic oscillation measurements is small, but that a bias is introduced to parameters which depend on the full shape of our correlations. We combine a model of this contamination in the cross-correlation with a new model we introduce here for the autocorrelation. These are parametrized by three parameters, which, when included in a joint fit to both correlation functions, successfully eliminate any impact of redshift errors on our full-shape constraints. We also present a strategy for removing this contamination from real data, by removing 0.3 per cent of correlating pairs
Personality Dynamics and Trait Change on the Year Abroad
No full textOur aims were to (a) investigate personality change as a function of context (abroad vs. at-home), (b) examine short- (state), medium- (facet), and longer-term (trait) personality variability, and (c) explore linkages between state dynamics and trait change over one year. 180 students from 12 universities were either at-home or living abroad across 32 destinations. Big Five traits were assessed termly; select facet-level traits monthly. Experience sampling was used to capture momentary responses. While sojourners became more agreeable, curious, and less anxious than non-sojourners, widespread change was not observed. Among the modelled personality dynamics indices (mean states, relative SDs, situation contingencies), mean states were the most consistent predictors of trait change, suggesting state-like trait manifestations play a role in personality development
Brachiopod giants from the Mississippian (Asbian) of western Ireland: Fossil bioarchives of seasonality and symbiosis and far-field harbingers of climate change
No full textBrachiopod species of Gigantoproductus have long fascinated researchers, not only because of their exceptional size and thick shell, but also as unparalleled bioarchives for palaeoecological and palaeoclimatic information. In this paper, we describe faunas containing Gigantoproductus semiglobosus from upper Visean (upper Asbian) successions in two regions of western Ireland, and report geochemical analyses that improve understanding of the palaeobiology of these brachiopods. The two regions are the Burren, where the Aillwee Member (Burren Formation) comprises thick-bedded cyclic bioclastic packstone to grainstone, interpreted as the deposits in predominantly shallow-water (subtidal) marine environments with episodic subaerial exposure, and the Aran Islands, where the Slievenaglasha Formation comprises cyclic crinoidal limestones with chert, deposited in slightly deeper water conditions. Shallowing upward fourth-order cycles in both regions have previously been interpreted as being under a glacioeustatic control. Reconstructed δ13Corg and δ15Norg of soft tissues of G. semiglobosus are respectively −29.0 to −30.1 ‰ (VPDB) and − 1.4 ‰ and + 6.1 ‰ (Air) and serve as proxies for identifying photosymbiotic relationships and a mixotroph lifestyle for this species. Well-preserved δ18Ocarb profiles record high seasonal variations (Δδ18O = 0.9 to 1.9 ‰ corresponding to a ΔT = 4 to 11 °C) for palaeoequatorial settings as a far-field proxy of the onset of sustained Gondwanan glaciation in the late Visean and provide evidence of warm tropics during the glaciation. The δ13Ccarb profiles are mostly controlled by local influences and changes in productivity. Our geochemical analyses of growth patterns, seasonal variation, diet and endosymbiosis in G. semiglobosus, sheds new light on the paradox of these unusual brachiopods, and provides a greater understanding of their massive size
Confidential Computing on Heterogeneous CPU-GPU Systems: Survey and Future Directions
No full textIn recent years, the widespread informatization and rapid data explosion have increased the demand for high-performance heterogeneous systems that integrate multiple computing cores such as CPUs, Graphics Processing Units (GPUs), Application Specific Integrated Circuits (ASICs), and Field Programmable Gate Arrays (FPGAs). The combination of CPU and GPU is particularly popular due to its versatility. However, these heterogeneous systems face significant security and privacy risks. Advances in privacy-preserving techniques, especially hardware-based Trusted Execution Environments (TEEs), offer effective protection for GPU applications. Nonetheless, the potential security risks involved in extending TEEs to GPUs in heterogeneous systems remain uncertain and need further investigation. To investigate these risks in depth, we study the existing popular GPU TEE designs and summarize and compare their key implications. Additionally, we review existing powerful attacks on GPUs and traditional TEEs deployed on CPUs, along with the efforts to mitigate these threats. We identify potential attack surfaces introduced by GPU TEEs and provide insights into key considerations for designing secure GPU TEEs. This survey is timely as new TEEs for heterogeneous systems, particularly GPUs, are being developed, highlighting the need to understand potential security threats and build both efficient and secure systems
Brick is Warmer than Concrete: Care for Urban Aesthetics in Cities with Violent Pasts
No full textIn sociology, aesthetics have become an important lens for exploring the sensory dimensions of political and economic processes, with research on urban aesthetics contributing significantly to this field. However, much of this work focuses on how aesthetic forms serve the interests of political and economic elites, portraying aesthetic value as a direct product of political ideologies. While these approaches have shown that urban aesthetics are shaped by power struggles, they pay limited theoretical attention to less straightforward aspects of aesthetic politics—such as cases where clashing values, imperatives, and commitments meet. This gap is particularly pronounced in places shaped by violent histories, where the value of urban beauty might be inevitably entangled with loss, ambivalence, and co-existence with unwanted materialities. This article proposes an approach that foregrounds the dilemmas and compromises inherent in urban aesthetic politics, focusing on the varied practices through which people negotiate how to care for urban aesthetic value over time. I develop this approach through a case study of Klaipėda, Lithuania—a city shaped by layered aesthetic transformations, from state annexation to socialist modernisation to post-Soviet nation-building and Europeanisation. Using mixed-methods research, the article highlights differences in how people articulate what counts as good and bad aesthetics and which forms of material care—or neglect—are “appropriate” to sustain the city’s desirable aesthetic appeal. In doing so, the article reveals complex gradations of value underlying seemingly coherent aesthetic ideals of Europeanness
Comparative Study of Reproducibility of Ranked Set Sampling Methods using Predictive Inference
No full textRanked set sampling (RSS) is an important survey technique aimed at efficient estimation of population characteristics. Various RSS methods can be used to collect an RSS sample, but the reproducibility of estimates using these methods remains unexplored. Reproducibility refers to obtaining similar estimates when the survey is repeated under identical conditions. This study compares the reproducibility of population mean estimates using four basic RSS methods: classical RSS (RSS), Median RSS (MRSS), Extreme RSS (ERSS), and Paired RSS (PRSS). We assess the reproducibility of these methods using Nonparametric Predictive Inference (NPI) bootstrapping. Simulations are conducted for varying sample sizes with both perfect and imperfect rankings, and results are compared for weak and strong associations between the study and concomitant variables. Additionally, we apply these methods to agricultural data from Punjab, India. Our findings indicate that MRSS provides the best reproducibility for population mean estimates, while ERSS performs the worst in this regard
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