1,232 research outputs found
Thalamocortical synchronization and cognition: implications for schizophrenia?
Cognitive deficits are a core dysfunction in schizophrenia. In this issue of Neuron, Parnaudeau et al. (2013) investigated synchronization in thalamocortical pathways in an animal model to address the disconnection between brain regions as a mechanism for working memory impairments in the disorder.implicated dysfunctional neural oscillations in the explanation of cognitive deficits and certain clinical symptoms of schizophrenia. Specifically, we will focus on findings that have examined neural oscillations during 1) perceptual processing, 2) working memory and executive processes and 3) spontaneous activity. The importance of the development of paradigms suitable for human and animal models is discussed as well as the search for mechanistic explanation for oscillatory dysfunctions
Layer-by-layer biofabrication of coronary covered stents with clickable elastin-like recombinamers
Producción CientíficaCoronary artery disease is the leading cause of death around the world. Endovascular stenting is the preferred treatment option to restore blood flow in the coronary arteries due to the lower perioperative morbidity when compared with more invasive treatment options. However, stent failure is still a major clinical problem, and further technological solutions are required to improve the performance of current stents. Here, we developed coronary stents covered with elastin-like recombinamers (ELRs) by exploiting a layer-by-layer technique combined with catalyst-free click chemistry. The resulting ELR-covered stents were intact after an in vitro simulated implantation procedure by balloon dilatation, which evidenced the elastic performance of the membrane. Additionally, the stents were mechanically stable under high flow conditions, which is in agreement with the covalent and stable nature of the click chemistry crosslinking strategy exploited during the ELR-membrane manufacturing and the successful embedding of the stent. Minimal platelet adhesion was detected after blood exposure in a Chandler loop as shown by scanning electron microscopy. The seeding of human endothelial progenitor cells (EPCs) on the ELR-membranes resulted in a confluent endothelial layer. These results prove the potential of this strategy to develop an advanced generation of coronary stents, with a stable and bioactive elastin-like membrane to exclude the atherosclerotic plaque from the blood stream or to seal coronary perforations and aneurysms, while providing a luminal surface with minimal platelet adhesion and favouring endothelialization.German federal and state governments (project StUpPD_330-18)Ministerio de Economía, Industria y Competitividad (projects PCIN-2015-010 / MAT2016-78903-R)Junta de Castilla y León (project VA317P18
Multiband Superconductivity in KFe2As2: Evidence for one Isotropic and several Liliputian Energy Gaps
We report a detailed low-temperature thermodynamic investigation (heat
capacity and magnetization) of the superconducting state of KFe2As2 for H || c
axis. Our measurements reveal that the properties of KFe2As2 are dominated by a
relatively large nodeless energy gap (Delta?0 = 1.9 kBTc) which excludes dx2-y2
symmetry. We prove the existence of several additional extremely small gaps
(?Delta0 < 1.0 kBTc) that have a profound impact on the low-temperature and
low-field behavior, similar to MgB2, CeCoIn5 and PrOs4Sb12. The zero-field heat
capacity is analyzed in a realistic self-consistent 4-band BCS model which
qualitatively reproduces the recent laser ARPES results of Okazaki et al.
(Science 337 (2012) 1314). Our results show that extremely low-temperature
measurements, i.e. T < 0.1 K, will be required in order to resolve the question
of the existence of line nodes in this compound.Comment: 7 pages, 6 figure
Low-Dimensional Hyperbolic Knowledge Graph Embeddings
Knowledge graph (KG) embeddings learn low-dimensional representations of
entities and relations to predict missing facts. KGs often exhibit hierarchical
and logical patterns which must be preserved in the embedding space. For
hierarchical data, hyperbolic embedding methods have shown promise for
high-fidelity and parsimonious representations. However, existing hyperbolic
embedding methods do not account for the rich logical patterns in KGs. In this
work, we introduce a class of hyperbolic KG embedding models that
simultaneously capture hierarchical and logical patterns. Our approach combines
hyperbolic reflections and rotations with attention to model complex relational
patterns. Experimental results on standard KG benchmarks show that our method
improves over previous Euclidean- and hyperbolic-based efforts by up to 6.1% in
mean reciprocal rank (MRR) in low dimensions. Furthermore, we observe that
different geometric transformations capture different types of relations while
attention-based transformations generalize to multiple relations. In high
dimensions, our approach yields new state-of-the-art MRRs of 49.6% on WN18RR
and 57.7% on YAGO3-10
Interplay of stripe and double-Q magnetism with superconductivity in under the influence of magnetic fields
At
undergoes a
novel first-order transition from a four-fold symmetric double-Q magnetic phase
to a two-fold symmetric single-Q phase, which was argued to occur
simultaneously with the onset of superconductivity (B\"ohmer et al., Nat. Comm.
6, 7911 (2015)). Here, by applying magnetic fields up to 10T, we investigate in
more detail the interplay of superconductivity with this magneto-structural
transition using a combination of high-resolution thermal-expansion and
heat-capacity measurements. We find that a magnetic field suppresses the
reentrance of the single-Q orthorhombic phase more strongly than the
superconducting transition, resulting in a splitting of the zero-field
first-order transition. The suppression rate of the orthorhombic reentrance
transition is stronger for out-of-plane than for in-plane fields and scales
with the anisotropy of the superconducting state. These effects are captured
within a phenomenological Ginzburg-Landau model, strongly suggesting that the
suppression of the reentrant orthorhombic single-Q phase is primarily linked to
the field-induced weakening of the superconducting order. Not captured by this
model is however a strong reduction of the orthorhombic distortion for
out-of-plane fields, which deserves further theoretical attention
El Niño‐driven oxygenation impacts Peruvian shelf iron supply to the South Pacific Ocean
Upwelling ocean currents associated with oxygen minimum zones (OMZs) supply nutrients fuelling intense marine productivity. Perturbations in the extent and intensity of OMZs are projected in the future, but it is currently uncertain how this will impact fluxes of redox‐sensitive trace metal micronutrients to the surface ocean. Here we report seawater concentrations of Fe, Mn, Co, Cd, and Ni alongside the redox indicator iodide/iodate in the Peruvian OMZ during the 2015 El Niño event. The El Niño drove atypical upwelling of oxygen‐enriched water over the Peruvian Shelf, resulting in oxidized iodine and strongly depleted Fe (II), total dissolved Fe, and reactive particulate Fe concentrations relative to non‐El Niño conditions. Observations of Fe were matched by the redox‐sensitive micronutrients Co and Mn, but not by non‐redox‐sensitive Cd and Ni. These observations demonstrate that oxygenation of OMZs significantly reduces water column inventories of redox‐sensitive micronutrients, with potential impacts on ocean productivity.
Plain Language Summary
Some trace metals, including iron, are essential micronutrients for phytoplankton growth. However, the solubility of iron is very low under oxygenated conditions. Consequently, restricted iron availability in oxygen‐rich seawater can limit phytoplankton growth in the ocean, including in the Eastern Tropical South Pacific. Under typical conditions, depleted oxygen on the South American continental shelf is generally thought to enhance iron supply to the ocean, fuelling phytoplankton productivity in overlying waters. However, the impact of changes in oxygenation, which are predicted to occur in the future, are not known. The 2015 El Niño event led to unusually high oxygen on the Peruvian shelf, offering a system‐scale test on how oxygen influences seawater iron concentrations. We show that El Niño‐driven oxygenation resulted in marked decreases in iron and other metals sensitive to oxygen (cobalt and manganese), whilst metals not sensitive to oxygen (cadmium and nickel) were unaffected. The measured reductions in iron may have led to decreased phytoplankton productivity
Combining optimized image processing with dual axis rotational angiography : toward low-dose invasive coronary angiography
Background Dual axis rotational coronary angiography procedures. Methods and Results Twenty patients were examined using to 2.22 mSv in procedures, where the latter is further reduced to 1.79 mSv when excluding ventriculography. Conclusions During invasive coronary angiography, procedures, using 1 effective dose conversion factor of 0.30 mSvGy(-1)cm(-2) is feasible
Macroporous click-elastin-like hydrogels for tissue engineering applications
Producción CientíficaElastin is a key extracellular matrix (ECM) protein that imparts functional elasticity to tissues and therefore an attractive candidate for bioengineering materials. Genetically engineered elastin-like recombinamers (ELRs) maintain inherent properties of the natural elastin (e.g. elastic behavior, bioactivity, low thrombogenicity, inverse temperature transition) while featuring precisely controlled composition, the possibility for biofunctionalization and non-animal origin. Recently the chemical modification of ELRs to enable their crosslinking via a catalyst-free click chemistry reaction, has further widened their applicability for tissue engineering. Despite these outstanding properties, the generation of macroporous click-ELR scaffolds with controlled, interconnected porosity has remained elusive so far. This significantly limits the potential of these materials as the porosity has a crucial role on cell infiltration, proliferation and ECM formation. In this study we propose a strategy to overcome this issue by adapting the salt leaching/gas foaming technique to click-ELRs. As result, macroporous hydrogels with tuned pore size and mechanical properties in the range of many native tissues were reproducibly obtained as demonstrated by rheological measurements and quantitative analysis of fluorescence, scanning electron and two-photon microscopy images. Additionally, the appropriate size and interconnectivity of the pores enabled smooth muscle cells to migrate into the click-ELR scaffolds and deposit extracellular matrix. The macroporous structure together with the elastic performance and bioactive character of ELRs, the specificity and non-toxic character of the catalyst-free click-chemistry reaction, make these scaffolds promising candidates for applications in tissue regeneration. This work expands the potential use of ELRs and click chemistry systems in general in different biomedical fields.Ministerio de Economía, Industria y Competitividad (Projects MAT2013-42473-R, MAT2015-68901-R, MAT2016- 78903-R)Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA313U14, VA015U16 y PCIN-2015-010)gobierno federal y estatal de Alemania en el marco del Programa de Posición Rotacional i³tm (2014-R4-01) y del Programa START de la Facultad de Medicina de la Universidad de Aachen (proyecto nº 691713),el centro de imágenes del Centro Interdisciplinario de Investigación Clínica (IZKF) de la Facultad de Medicina de la Universidad de Aache
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