5,189 research outputs found
Horizontal flow fields observed in Hinode G-band images. I. Methods
Context: The interaction of plasma motions and magnetic fields is an
important mechanism, which drives solar activity in all its facets. For
example, photospheric flows are responsible for the advection of magnetic flux,
the redistribution of flux during the decay of sunspots, and the built-up of
magnetic shear in flaring active regions. Aims: Systematic studies based on
G-band data from the Japanese Hinode mission provide the means to gather
statistical properties of horizontal flow fields. This facilitates comparative
studies of solar features, e.g., G-band bright points, magnetic knots, pores,
and sunspots at various stages of evolution and in distinct magnetic
environments, thus, enhancing our understanding of the dynamic Sun. Methods: We
adapted Local Correlation Tracking (LCT) to measure horizontal flow fields
based on G-band images obtained with the Solar Optical Telescope on board
Hinode. In total about 200 time-series with a duration between 1-16 h and a
cadence between 15-90 s were analyzed. Selecting both a high-cadence (dt = 15
s) and a long-duration (dT = 16 h) time-series enabled us to optimize and
validate the LCT input parameters, hence, ensuring a robust, reliable, uniform,
and accurate processing of a huge data volume. Results: The LCT algorithm
produces best results for G-band images having a cadence of 60-90 s. If the
cadence is lower, the velocity of slowly moving features will not be reliably
detected. If the cadence is higher, the scene on the Sun will have evolved too
much to bear any resemblance with the earlier situation. Consequently, in both
instances horizontal proper motions are underestimated. The most reliable and
yet detailed flow maps are produced using a Gaussian kernel with a size of 2560
km x 2560 km and a full-width-at-half-maximum (FWHM) of 1200 km (corresponding
to the size of a typical granule) as sampling window.Comment: 12 pages, 8 figures, 4 tables, accepted for publication in Astronomy
and Astrophysic
Strategies and actions for achieving carbon neutrality in Portuguese residential buildings by 2050
As a crucial step in addressing the climate emergency and enhancing energy security, the European Union has set ambitious targets to decarbonise its economy by 2050. While the building sector plays a pivotal role in this transition, being accountable for 36% of the EU’s total carbon emissions, it shows a renovation rate below 1% per year, which is clearly insufficient. To address this challenge, this study uses the cost-optimal methodology from private and social perspectives to assess the cost-effectiveness and environmental impact of five renovation packages with passive and active solutions currently available on the Portuguese market. The results demonstrated that from both perspectives, optimal combinations of market solutions were generally cost-effective and could lead to a 90–99% reduction in energy needs and even to zero carbon levels. Nevertheless, beyond cost-effectiveness, consideration of co-benefits, e.g., social and health improvements, is also crucial, requiring government action. To drive these essential changes, effective policy measures are imperative. Recommendations encompass robust regulatory frameworks, financial support mechanisms, knowledge dissemination, and a shift towards broader-scale renovation. For carbon reduction to be economically attractive, fostering innovative business models and leveraging legal instruments to tackle complex scenarios are needed.This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the R & D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020 and under the Associate Laboratory Advanced Production and Intelligent Systems ARISE under reference LA/P/0112/2020. The work was also partly financed by the program Portugal Norte 2020-Projetos Estruturados I & D, with the reference NORTE 01-0145-FEDER000058—ZeroSkin+ project
Second-Harmonic Generation in Silicon Nitride Ring Resonators
The emerging field of silicon photonics seeks to unify the high bandwidth of
optical communications with CMOS microelectronic circuits. Many components have
been demonstrated for on-chip optical communications, including those that
utilize the nonlinear optical properties of silicon[1, 2], silicon dioxide[3,
4] and silicon nitride[5, 6]. Processes such as second harmonic generation,
which are enabled by the second-order susceptibility, have not been developed
since the bulk vanishes in these centrosymmetric CMOS materials.
Generating the lowest-order nonlinearity would open the window to a new array
of CMOS-compatible optical devices capable of nonlinear functionalities not
achievable with the? response such as electro-optic modulation, sum
frequency up-conversion, and difference frequency generation. Here we
demonstrate second harmonic (SH) generation in CMOS compatible integrated
silicon nitride (Si3N4) waveguides. The response is induced in the
centrosymmetric material by using the nanoscale structure to break the bulk
symmetry. We use a high quality factor Q ring resonator cavity to enhance the
efficiency of the nonlinear optical process and detect SH output with milliwatt
input powers.Comment: 4 pages, 3 figure
The effect of microstructure of unidirectional fibre-reinforced composites on mechanical properties under transverse loading:a review
Australian older adults\u27 views on using social media for reducing social isolation and loneliness in hearing impaired older adults: A community conversation
Objective(s): The objective of this study was to conduct a community conversation to identify the views of the community members when designing an online community using Facebook to support the psychosocial well-being of hearing-impaired older adults. Methods: A community conversation was held with 40 older adults aged more than 60 years. The participants were divided into groups of five and asked to discuss three open-ended questions. The researchers facilitated the discussions. Results: The overwhelming response from this group was that they did not use Facebook or social media as a tool for social connection and did not see the benefits of social media applications. They preferred phone calls or in-person events to maintain their social relationships. Conclusions: Implications for areas of future research and interventions that target loneliness in older adults are discussed
Avidity of influenza-specific memory CD8+ T-cell populations decays over time compromising antiviral immunity
Decline of cell-mediated immunity is often attributed to decaying T-cell numbers and their distribution in peripheral organs. This study examined the hypothesis that qualitative as well as quantitative changes contribute to the declining efficacy of CD8+ T-cell memory. Using a model of influenza virus infection, where loss of protective CD8+ T-cell immunity was observed 6 months postinfection, we found no decline in antigen-specific T-cell numbers or migration to the site of secondary infection. There was, however, a large reduction in antigen-specific CD8+ T-cell degranulation, cytokine secretion, and polyfunctionality. A profound loss of high-avidity T cells over time indicated that failure to confer protective immunity resulted from the inferior functional capacity of remaining low avidity cells. These data imply that high-avidity central memory T cells wane with declining antigen levels, leaving lower avidity T cells with reduced functional capabilities
Poder local como ator fundamental no processo de reabilitação energética do parque habitacional
Estamos atrasados na reabilitação energética dos edifícios residenciais,
um desígnio urgente quando pensamos na descarbonização e também na
resolução de várias questões sociais. Perante desafios legais, financeiros,
organizacionais e de sensibilização, o poder local pode ter um papel
fundamental neste processo.UIDB/04029/202
Decoherence-free evolution of time-dependent superposition states of two-level systems and thermal effects
In this paper we detail some results advanced in a recent letter [Prado et
al., Phys. Rev. Lett. 102 073008 (2009)] showing how to engineer reservoirs for
two-level systems at absolute zero by means of a time-dependent master equation
leading to a nonstationary superposition equilibrium state. We also present a
general recipe showing how to build nonadiabatic coherent evolutions of a
fermionic system interacting with a bosonic mode and investigate the influence
of thermal reservoirs at finite temperature on the fidelity of the protected
superposition state. Our analytical results are supported by numerical analysis
of the full Hamiltonian model.Comment: 7 pages, 4 figure
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical science
A Combined mRNA- and miRNA-Sequencing Approach Reveals miRNAs as Potential Regulators of the Small Intestinal Transcriptome in Celiac Disease
Celiac disease (CeD) is triggered by gluten and results in inflammation and villous atrophy of the small intestine. We aimed to explore the role of miRNA-mediated deregulation of the transcriptome in CeD. Duodenal biopsies of CeD patients (n = 33) and control subjects (n = 10) were available for miRNA-sequencing, with RNA-sequencing also available for controls (n = 5) and CeD (n = 6). Differential expression analysis was performed to select CeD-associated miRNAs and genes. MiRNA‒target transcript pairs selected from public databases that also displayed a strong negative expression correlation in the current dataset (R < −0.7) were used to construct a CeD miRNA‒target transcript interaction network. The network includes 2030 miRNA‒target transcript interactions, including 423 experimentally validated pairs. Pathway analysis found that interactions are involved in immune-related pathways (e.g., interferon signaling) and metabolic pathways (e.g., lipid metabolism). The network includes 13 genes previously prioritized to be causally deregulated by CeD-associated genomic variants, including STAT1. CeD-associated miRNAs might play a role in promoting inflammation and decreasing lipid metabolism in the small intestine, thereby contributing unbalanced cell turnover in the intestinal crypt. Some CeD-associated miRNAs deregulate genes that are also affected by genomic CeD-risk variants, adding an additional layer of complexity to the deregulated transcriptome in CeD
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