114 research outputs found
Hyperglycemia-induced inhibition of DJ-1 expression compromised the effectiveness of ischemic postconditioning cardioprotection in rats
published_or_final_versio
Frame Theory for Signal Processing in Psychoacoustics
This review chapter aims to strengthen the link between frame theory and
signal processing tasks in psychoacoustics. On the one side, the basic concepts
of frame theory are presented and some proofs are provided to explain those
concepts in some detail. The goal is to reveal to hearing scientists how this
mathematical theory could be relevant for their research. In particular, we
focus on frame theory in a filter bank approach, which is probably the most
relevant view-point for audio signal processing. On the other side, basic
psychoacoustic concepts are presented to stimulate mathematicians to apply
their knowledge in this field
Antiferromagnetism and single-particle properties in the two-dimensional half-filled Hubbard model: a non-linear sigma model approach
We describe a low-temperature approach to the two-dimensional half-filled
Hubbard model which allows us to study both antiferromagnetism and
single-particle properties. This approach ignores amplitude fluctuations of the
antiferromagnetic (AF) order parameter and is valid below a crossover
temperature which marks the onset of AF short-range order. Directional
fluctuations (spin waves) are described by a non-linear sigma model
(NLM) that we derive from the Hubbard model. At zero temperature and
weak coupling, our results are typical of a Slater antiferromagnet. The AF gap
is exponentially small; there are well-defined Bogoliubov quasi-particles
(QP's) (carrying most of the spectral weight) coexisting with a high-energy
incoherent excitation background. As increases, the Slater antiferromagnet
progressively becomes a Mott-Heisenberg antiferromagnet. The Bogoliubov bands
evolve into Mott-Hubbard bands separated by a large AF gap. A significant
fraction of spectral weight is transferred from the Bogoliubov QP's to
incoherent excitations. At finite temperature, there is a metal-insulator
transition between a pseudogap phase at weak coupling and a Mott-Hubbard
insulator at strong coupling. Finally, we point out that our results
straightforwardly translate to the half-filled attractive Hubbard model, where
the charge and pairing fluctuations combine to
form an order parameter with SO(3) symmetry.Comment: Revtex4, 19 pages, 14 figures; (v2) final version as publishe
Holocene El Niño–Southern Oscillation variability reflected in subtropical Australian precipitation
The La Niña and El Niño phases of the El Niño-Southern Oscillation (ENSO) have major impacts on regional rainfall patterns around the globe, with substantial environmental, societal and economic implications. Long-term perspectives on ENSO behaviour, under changing background conditions, are essential to anticipating how ENSO phases may respond under future climate scenarios. Here, we derive a 7700-year, quantitative precipitation record using carbon isotope ratios from a single species of leaf preserved in lake sediments from subtropical eastern Australia. We find a generally wet (more La Niña-like) mid-Holocene that shifted towards drier and more variable climates after 3200 cal. yr BP, primarily driven by increasing frequency and strength of the El Niño phase. Climate model simulations implicate a progressive orbitally-driven weakening of the Pacific Walker Circulation as contributing to this change. At centennial scales, high rainfall characterised the Little Ice Age (~1450–1850 CE) in subtropical eastern Australia, contrasting with oceanic proxies that suggest El Niño-like conditions prevail during this period. Our data provide a new western Pacific perspective on Holocene ENSO variability and highlight the need to address ENSO reconstruction with a geographically diverse network of sites to characterise how both ENSO, and its impacts, vary in a changing climate
Multifocal occurrence of extra-abdominal desmoid type fibromatosis – A rare manifestation. A clinicopathological study of 6 sporadic cases and 1 hereditary case
Desmoid-type fibromatosis, also called desmoid tumor, is a locally aggressive myofibroblastic neoplasm that usually arises in deep soft tissue with significant potential for local recurrence. It displays an unpredictable clinical course. β-Catenin, the genetic key player of desmoid tumors shows nuclear accumulation due to mutations that preve
Management of multidrug resistant Gram-negative bacilli infections in solid organ transplant recipients: SET/GESITRA-SEIMC/REIPI recommendations
Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant (MDR) Gram-negative bacilli (GNB), as they are frequently exposed to antibiotics and the healthcare setting, and are regulary subject to invasive procedures. Nevertheless, no recommendations concerning prevention and treatment are available. A panel of experts revised the available evidence; this document summarizes their recommendations: (1) it is important to characterize the isolate´s phenotypic and genotypic resistance profile; (2) overall, donor colonization should not constitute a contraindication to transplantation, although active infected kidney and lung grafts should be avoided; (3) recipient colonization is associated with an increased risk of infection, but is not a contraindication to transplantation; (4) different surgical prophylaxis regimens are not recommended for patients colonized with carbapenem-resistant GNB; (5) timely detection of carriers, contact isolation precautions, hand hygiene compliance and antibiotic control policies are important preventive measures; (6) there is not sufficient data to recommend intestinal decolonization; (7) colonized lung transplant recipients could benefit from prophylactic inhaled antibiotics, specially for Pseudomonas aeruginosa; (8) colonized SOT recipients should receive an empirical treatment which includes active antibiotics, and directed therapy should be adjusted according to susceptibility study results and the severity of the infection.J.T.S. holds a research contract from the Fundación para la Formación e Investigación de los Profesionales de la Salud de Extremadura (FundeSalud), Instituto de Salud Carlos III. M.F.R. holds a clinical research contract “Juan Rodés” (JR14/00036) from the Spanish Ministry of Economy and Competitiveness, Instituto de Salud Carlos III
Placental transfer of pyrimethamine studied in an ex vivo placental perfusion model.
Pyrimethamine is used as and anti-infectious agent because of its antifolate properties. Its action is synergistic with that of dapsone and sulfamides on Toxoplasma gondii. The goal of the present study was to evaluate the placental transfer of pyrimethamine in an ex vivo model of perfused human placental cotyledon at term. Human placentas were perfused according to the slightly modified method of Schneider. The pyrimethamine fetal transfer rate was approximately 30%, while cotyledon clearance was about 1.8 ml/min. The placental transfer of pyrimethamine seems to be independent of the maternal concentrations of pyrimethamine, suggesting passive diffusion mechanisms or a nonsaturable active transport at the tested concentrations
Unravelling contamination signals in biogenic silica oxygen isotope composition : the role of major and trace element geochemistry
The oxygen isotope composition of diatom silica ( 18Odiatom) provides valuable information for palaeoclimate studies where carbonate proxies are either rare or absent in many lakes and ocean sediments. Unfortunately, mineral and rock fragments found alongside diatoms in most sediments can be problematic as the method used will liberate oxygen from all components within the sediment, producing both high-frequency noise and low-frequency excursions that can resemble climate signals. Removal of mineral contamination to date has largely relied upon the combination of chemical leaching and physical separation techniques (e.g. sieving, density). This combination can be inefficient and often significant proportions of contaminants are present in the purified diatom sample. Using electron optical imaging and whole-rock geochemistry on previously purified diatom samples, a mass balance approach has been developed whereby the types and proportions of residual contaminants are identified. By integrating this information with measured oxygen isotope ratios of the contaminants, it is then possible to remove contamination effects from the 18Odiatom record. Contamination effects relating to carbonates, tephra and silt are modelled for cores from Lake Tilo (Ethiopia) and Lake Baikal (Siberia). In both lakes the new modelled 18Odiatom curves show less high-frequency noise, thus enabling better resolution of low-frequency climate signal
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