326 research outputs found
Growth of the neo-aortic valve after the Ross procedure
Rovira Riera, AntoniPla general d'edifici, en un solar amb tres
façanes.
Fou construït al segle segle XIX, abans
de 1842.
Tot i que la seva autoria és encara dubtosa,
ha estat atribuït a Antoni Rovira Riera
Water splitting with polyoxometalate-treated photoanodes: Enhancing performance through sensitizer design
Visible light driven water oxidation has been demonstrated at near-neutral pH using photoanodes based on nanoporous films of TiO2, polyoxometalate (POM) water oxidation catalyst [{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2]10- (1), and both known photosensitizer [Ru(bpy)2(H4dpbpy)]2+ (P2) and the novel crown ether functionalized dye [Ru(5-crownphen)2(H2dpbpy)] (H22). Both triads, containing catalyst 1, and catalyst-free dyads, produce O2 with high faradaic efficiencies (80 to 94%), but presence of catalyst enhances quantum yield by up to 190% (maximum 0.39%). New sensitizer H22 absorbs light more strongly than P2, and increases O2 quantum yields by up to 270%. TiO2-2 based photoelectrodes are also more stable to desorption of active species than TiO2-P2: losses of catalyst 1 are halved when pH > TiO2 point-of-zero charge (pzc), and losses of sensitizer reduced below the pzc (no catalyst is lost when pH < pzc). For the triads, quantum yields of O2 are higher at pH 5.8 than at pH 7.2, opposing the trend observed for 1 under homogeneous conditions. This is ascribed to lower stability of the dye oxidized states at higher pH, and less efficient electron transfer to TiO2, and is also consistent with the 4th 1-to-dye electron transfer limiting performance rather than catalyst TOFmax. Transient absorption reveals that TiO2-2-1 has similar 1st electron transfer dynamics to TiO2-P2-1, with rapid (ps timescale) formation of long-lived TiO2(e-)-2-1(h+) charge separated states, and demonstrates that metallation of the crown ether groups (Na+/Mg2+) has little or no effect on electron transfer from 1 to 2. The most widely relevant findings of this study are therefore: (i) increased dye extinction coefficients and binding stability significantly improve performance in dye-sensitized water splitting systems; (ii) binding of POMs to electrode surfaces can be stabilized through use of recognition groups; (iii) the optimal homogeneous and TiO2-bound operating pHs of a catalyst may not be the same; and (iv) dye-sensitized TiO2 can oxidize water without a catalyst
Viral to metazoan marine plankton nucleotide sequences from the Tara Oceans expedition
A unique collection of oceanic samples was gathered by the Tara Oceans expeditions (2009-2013), targeting plankton organisms ranging from viruses to metazoans, and providing rich environmental context measurements. Thanks to recent advances in the field of genomics, extensive sequencing has been performed for a deep genomic analysis of this huge collection of samples. A strategy based on different approaches, such as metabarcoding, metagenomics, single-cell genomics and metatranscriptomics, has been chosen for analysis of size-fractionated plankton communities. Here, we provide detailed procedures applied for genomic data generation, from nucleic acids extraction to sequence production, and we describe registries of genomics datasets available at the European Nucleotide Archive (ENA, www.ebi.ac.uk/ena). The association of these metadata to the experimental procedures applied for their generation will help the scientific community to access these data and facilitate their analysis. This paper complements other efforts to provide a full description of experiments and open science resources generated from the Tara Oceans project, further extending their value for the study of the world's planktonic ecosystems
Development of quality metrics for ambulatory pediatric cardiology: Transposition of the great arteries after arterial switch operation
ObjectiveTo develop quality metrics (QMs) for the ambulatory care of patients with transposition of the great arteries following arterial switch operation (TGA/ASO).DesignUnder the auspices of the American College of Cardiology Adult Congenital and Pediatric Cardiology (ACPC) Steering committee, the TGA/ASO team generated candidate QMs related to TGA/ASO ambulatory care. Candidate QMs were submitted to the ACPC Steering Committee and were reviewed for validity and feasibility using individual expert panel member scoring according to the RANDâ UCLA methodology. QMs were then made available for review by the entire ACC ACPC during an â open comment period.â Final approval of each QM was provided by a vote of the ACC ACPC Council.PatientsPatients with TGA who had undergone an ASO were included. Patients with complex transposition were excluded.ResultsTwelve candidate QMs were generated. Seven metrics passed the RANDâ UCLA process. Four passed the â open comment periodâ and were ultimately approved by the Council. These included: (1) at least 1 echocardiogram performed during the first year of life reporting on the function, aortic dimension, degree of neoaortic valve insufficiency, the patency of the systemic and pulmonary outflows, the patency of the branch pulmonary arteries and coronary arteries, (2) neurodevelopmental (ND) assessment after ASO; (3) lipid profile by age 11 years; and (4) documentation of a transition of care plan to an adult congenital heart disease (CHD) provider by 18 years of age.ConclusionsApplication of the RANDâ UCLA methodology and linkage of this methodology to the ACPC approval process led to successful generation of 4 QMs relevant to the care of TGA/ASO pediatric patients in the ambulatory setting. These metrics have now been incorporated into the ACPC Quality Network providing guidance for the care of TGA/ASO patients across 30 CHD centers.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142334/1/chd12540_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142334/2/chd12540.pd
On-surface synthesis of a doubly anti-aromatic carbon allotrope
Synthetic carbon allotropes such as graphene, carbon nanotubes and fullerenes have revolutionized materials science and led to new technologies. Many hypothetical carbon allotropes have been discussed, but few have been studied experimentally. Recently, unconventional synthetic strategies such as dynamic covalent chemistry and on-surface synthesis have been used to create new forms of carbon, including γ-graphyne, fullerene polymers, biphenylene networks and cyclocarbons. Cyclo[N]carbons are molecular rings consisting of N carbon atoms; the three that have been reported to date (N = 10, 14 and 18) are doubly aromatic, which prompts the question: is it possible to prepare doubly anti-aromatic versions? Here we report the synthesis and characterization of an anti-aromatic carbon allotrope, cyclo[16]carbon, by using tip-induced on-surface chemistry. In addition to structural information from atomic force microscopy, we probed its electronic structure by recording orbital density maps with scanning tunnelling microscopy. The observation of bond-length alternation in cyclo[16]carbon confirms its double anti-aromaticity, in concordance with theory. The simple structure of C16 renders it an interesting model system for studying the limits of aromaticity, and its high reactivity makes it a promising precursor to novel carbon allotropes
Challenges in optics for Extremely Large Telescope instrumentation
We describe and summarize the optical challenges for future instrumentation
for Extremely Large Telescopes (ELTs). Knowing the complex instrumental
requirements is crucial for the successful design of 30-60m aperture
telescopes. After all, the success of ELTs will heavily rely on its
instrumentation and this, in turn, will depend on the ability to produce large
and ultra-precise optical components like light-weight mirrors, aspheric
lenses, segmented filters, and large gratings. New materials and manufacturing
processes are currently under study, both at research institutes and in
industry. In the present paper, we report on its progress with particular
emphasize on volume-phase-holographic gratings, photochromic materials,
sintered silicon-carbide mirrors, ion-beam figuring, ultra-precision surfaces,
and free-form optics. All are promising technologies opening new degrees of
freedom to optical designers. New optronic-mechanical systems will enable
efficient use of the very large focal planes. We also provide exploratory
descriptions of "old" and "new" optical technologies together with suggestions
to instrument designers to overcome some of the challenges placed by ELT
instrumentation.Comment: (Proc. OPTICON Key Technology Network Workshop, Rome 20-21 October
2005
VisDA 2022 Challenge: Domain Adaptation for Industrial Waste Sorting
Label-efficient and reliable semantic segmentation is essential for many
real-life applications, especially for industrial settings with high visual
diversity, such as waste sorting. In industrial waste sorting, one of the
biggest challenges is the extreme diversity of the input stream depending on
factors like the location of the sorting facility, the equipment available in
the facility, and the time of year, all of which significantly impact the
composition and visual appearance of the waste stream. These changes in the
data are called ``visual domains'', and label-efficient adaptation of models to
such domains is needed for successful semantic segmentation of industrial
waste. To test the abilities of computer vision models on this task, we present
the VisDA 2022 Challenge on Domain Adaptation for Industrial Waste Sorting. Our
challenge incorporates a fully-annotated waste sorting dataset, ZeroWaste,
collected from two real material recovery facilities in different locations and
seasons, as well as a novel procedurally generated synthetic waste sorting
dataset, SynthWaste. In this competition, we aim to answer two questions: 1)
can we leverage domain adaptation techniques to minimize the domain gap? and 2)
can synthetic data augmentation improve performance on this task and help adapt
to changing data distributions? The results of the competition show that
industrial waste detection poses a real domain adaptation problem, that domain
generalization techniques such as augmentations, ensembling, etc., improve the
overall performance on the unlabeled target domain examples, and that
leveraging synthetic data effectively remains an open problem. See
https://ai.bu.edu/visda-2022/Comment: Proceedings of Machine Learning Researc
Comportamiento funcional del polimorfonuclear en pacientes con hepatopatia alcohólica crónica
Las funciones de los leucocitos polimorfonucleares (PMNs) fueron estudiadas en diez pacientes con enfermedad hepática alcohólica crónica (E.H.A.C.). Los valores fueron comparados con aquellos obtenidos de los polimorfonucleares de once individuos sanos. Se encontraron diferencias significativas en: la activación inducida con endotoxina (estimada para la reducción in-vitro del Nitro-azul de Tetrazolio (NBT) (0,001 < P < 0,01), la quimiotaxis estimulada con endotoxina (0,02 < P < 0,05), la adherencia in-vitro (0,001 < P < 0,01) y la digestión in-vitro de Paracoccidioides brasiliensis a las 2 y media horas de incubación (0,001 < P < 0,01). Estos resultados muestran la existencia de defectos parciales en muchas de las funciones de los polimorfonucleares en nuestros pacientes con E.H.A.C
Large aperture telescope technology: a design for an active lightweight multi-segmented fold-out space mirror
© Copyright SPIE. Large aperture telescope technology (LATT) is a design study for a differential lidar (DIAL) system; the main investigation being into suitable methods, technologies and materials for a 4-metre diameter active mirror that can be stowed to fit into a typical launch vehicle (e.g. ROKOT launcher with ∼ 2.1-metre diameter cargo) and can self-deploy - in terms of both leaving the space vehicle and that the mirrors unfold and self-align to the correct optical form within the tolerances specified. The primary mirror requirements are: main wavelength of 935.5 nm, RMS corrected wavefront error of λ/6, optical surface roughness better than 5 nm, areal density of less than 16 kg/m2 and 1-2 mirror shape corrections per orbit. The primary mirror consists of 7 segments - a central hexagonal mirror and 6 square mirror petals which unfold to form the 4-meter diameter aperture. The focus of the UK LATT consortium for this European Space Agency (ESA) funded project is on using lightweighted aluminium or carbon-fibre-composite materials for the mirror substrate in preference to more traditional materials such as glass and ceramics; these materials have a high strength and stiffness to weight ratio, significantly reducing risk of damage due to launch forces and subsequent deployment in orbit. We present an overview of the design, which includes suitable actuators for wavefront correction, petal deployment mechanisms and lightweight mirror technologies. Preliminary testing results from manufactured lightweight mirror samples will also be summarised
MOONS: a Multi-Object Optical and Near-infrared Spectrograph for the VLT
MOONS is a new conceptual design for a Multi-Object Optical and Near-infrared
Spectrograph for the Very Large Telescope (VLT), selected by ESO for a Phase A
study. The baseline design consists of 1000 fibers deployable over a field of
view of 500 square arcmin, the largest patrol field offered by the Nasmyth
focus at the VLT. The total wavelength coverage is 0.8um-1.8um and two
resolution modes: medium resolution and high resolution. In the medium
resolution mode (R=4,000-6,000) the entire wavelength range 0.8um-1.8um is
observed simultaneously, while the high resolution mode covers simultaneously
three selected spectral regions: one around the CaII triplet (at R=8,000) to
measure radial velocities, and two regions at R=20,000 one in the J-band and
one in the H-band, for detailed measurements of chemical abundances. The grasp
of the 8.2m Very Large Telescope (VLT) combined with the large multiplex and
wavelength coverage of MOONS - extending into the near-IR - will provide the
observational power necessary to study galaxy formation and evolution over the
entire history of the Universe, from our Milky Way, through the redshift desert
and up to the epoch of re-ionization at z>8-9. At the same time, the high
spectral resolution mode will allow astronomers to study chemical abundances of
stars in our Galaxy, in particular in the highly obscured regions of the Bulge,
and provide the necessary follow-up of the Gaia mission. Such characteristics
and versatility make MOONS the long-awaited workhorse near-IR MOS for the VLT,
which will perfectly complement optical spectroscopy performed by FLAMES and
VIMOS.Comment: 9 pages, 5 figures. To appear in the proceedings of the SPIE
Astronomical Instrumentation + Telescopes conference, Amsterdam, 201
- …
