1,274 research outputs found
Neutrinoless double-β decay in the neutrino-extended standard model
We investigate neutrinoless double-beta decay (0 ) in the minimal extension of the standard model of particle physics, the SM, where gauge-singlet right-handed neutrinos give rise to Dirac and Majorana neutrino mass terms. We focus on the associated sterile neutrinos and argue that the usual evaluation of their contributions to 0 , based on mass-dependent nuclear matrix elements, is missing important contributions from neutrinos with ultrasoft and hard momenta. We identify the hadronic and nuclear matrix elements that enter the new contributions, and calculate all relevant nuclear matrix elements for 136Xe using the nuclear shell model. Finally, we illustrate the impact on 0 rates in specific neutrino mass models and show that the new contributions significantly alter the 0 rate in most parts of the SM parameter space
Granular fingering as a mechanism for ridge formation in debris avalanche deposits: Laboratory experiments and implications for Tutupaca volcano, Peru
The origin of subparallel, regularly-spaced longitudinal ridges often observed at the surface of volcanic and other rock avalanche deposits remains unclear. We addressed this issue through analogue laboratory experiments on flows of bi-disperse granular mixtures, because this type of flow is known to exhibit granular fingering that causes elongated structures resembling the ridges observed in nature. We considered four different mixtures of fine (300–400 µm) glass beads and coarse (600–710 µm to 900–1000 µm) angular crushed fruit stones, with particle size ratios of 1.9–2.7 and mass fractions of the coarse component of 5–50 wt%. The coarse particles segregated at the flow surface and accumulated at the front where flow instabilities with a well-defined wavelength grew. These formed granular fingers made of coarse-rich static margins delimiting fines-rich central channels. Coalescence of adjacent finger margins created regular spaced longitudinal ridges, which became topographic highs as finger channels drained at final emplacement stages. Three distinct deposit morphologies were observed: 1) Joined fingers with ridges were formed at low (= 1.9) size ratio and moderate (10–20 wt%) coarse fraction whereas 2) separate fingers or 3) poorly developed fingers, forming series of frontal lobes, were created at larger size ratios and/or higher coarse contents. Similar ridges and lobes are observed at the debris avalanche deposits of Tutupaca volcano, Peru, suggesting that the processes operating in the experiments can also occur in nature. This implies that volcanic (and non-volcanic) debris avalanches can behave as granular flows, which has important implications for interpretation of deposits and for modeling. Such behaviour may be acquired as the collapsing material disaggregates and forms a granular mixture composed by a right grain size distribution in which particle segregation can occur. Limited fragmentation and block sliding, or grain size distributions inappropriate for promoting granular fingering can explain why ridges are absent in many deposits
Succesive desetabilization of a dome complex constructed on an extinct, hydrothermally altered volcano: The Tutupaca Volcano case study (Southern Perú)
The Tutupaca volcanic complex (17°01' S, 70°21' W) is located to the south of Peru, and belongs to the Central volcanic Zone of the Andes. Tutupaca is composed of an old, hydrothermally altered and highly eroded basal edifice, and two younger twin peaks, located to the northern part of the complex (the Western and Eastern Tutupaca; Samaniego et al., 2015). The youngest Eastern edifice of Tutupaca is composed by at least 7 coalescing lava domes (named Dome I to VII by Manrique, 2013) and its associated deposits, among which are block-and-ash flow and debris avalanche deposits. We identifiedtwo debris avalanche deposits associated with this edifice. An older deposit (Azufre debris avalanche) was channelized in the valleys located to the E and SE of the volcano, reaching up to 3.5 km from its source region. This DAD occurred soon after the emplacement of the first Eastern Tutupaca domes (I, II,III) and its age was recently estimated by exposure dating at 6-8 ka BP. The younger deposit (Paipatja debris avalanche) outcrops immediately to the NE of the amphitheater and was associated with a large PDC deposits that was radiocarbon dated at 218 ± 14 a BP (Samaniego et al., 2015; Valderrama et al., 2016). Both debris avalanche deposits have two different sub-units: (1) the main subunit, hereafter called hydrothermal-altered blocks-rich debris avalanche deposit (HA-DAD) that is a whitish-yellow volcanic breccia with heterolithological and heterometric blocks, and (2) dome-rich debris avalanche (DR-DAD) sub unit, composed by non-altered dome blocks. In proximal areas, the DR-DAD overlaps the HA-DAD; whereas, in distal areas, these two units are mixed forming a hummocky and/or ridged topografphy. In addition to the similar facies of these DAD, we propose that the triggering mechanism for these debris avalanches was similar in both cases. The ascent of a dacitic magma, coupled with the fact that the Tutupaca dome complex was constructed on top of an older, hydrothermally-altered volcanic edifice, induced the destabilisation of the edifices, producing the debris avalanche and its related pyroclastic density currents
On the global economic potentials and marginal costs of non-renewable resources and the price of energy commodities
A model is presented in this work for simulating endogenously the evolution
of the marginal costs of production of energy carriers from non-renewable
resources, their consumption, depletion pathways and timescales. Such marginal
costs can be used to simulate the long term average price formation of energy
commodities. Drawing on previous work where a global database of energy
resource economic potentials was constructed, this work uses cost distributions
of non-renewable resources in order to evaluate global flows of energy
commodities. A mathematical framework is given to calculate endogenous flows of
energy resources given an exogenous commodity price path. This framework can be
used in reverse in order to calculate an exogenous marginal cost of production
of energy carriers given an exogenous carrier demand. Using rigid price
inelastic assumptions independent of the economy, these two approaches generate
limiting scenarios that depict extreme use of natural resources. This is useful
to characterise the current state and possible uses of remaining non-renewable
resources such as fossil fuels and natural uranium. The theory is however
designed for use within economic or technology models that allow technology
substitutions. In this work, it is implemented in the global power sector model
FTT:Power. Policy implications are given.Comment: 18 pages, 7 figures, 8 pages of supplementary informatio
Presence and evolution of NET markers and DAMPS in critically ill COVID-19 patients
Resumen del trabajo presentado en el 4th European Congress on Thrombosis and Haemostasis, celebrado en Gante (Bélgica), los días 14 y 15 de octubre de 2021Background: The coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection presents with a wide range of disease symptoms. In the more severe patients, COVID-19 is associated with respiratory failure, neutrophil extracellular trap (NET) formation, and multiple organ failure (MOF).
Aims: We investigated the presence and evolution of several damage associated molecular patterns (DAMPs) neutrophil markers and immune modulators in a group of 100 COVID-19-positive ICU patients.
Methods: Citrated plasma was collected from adult patients with confirmed COVID-19 by PCR detection of SARS-CoV-2 E and N-genes in nasopharyngeal swabs admitted to the intensive care unit (ICU) at Uppsala University hospital, Sweden. Written informed consent was obtained from the patients, or next of kin if the patient was unable to give consent. The Declaration of Helsinki and its subsequent revisions were followed. Plasma concentration of cell free DNA (cfDNA), extracellular histone H3 (H3), neutrophil elastase (NE), myeloperoxidase (MPO) and the cfDNA-MPO complex, and the immune modulators GAS6, and sAXL were measured in all COVID-19-positive and in COVID-19-negative patients and healthy controls. We determined marker levels upon admission, of their evolution, and correlation with disease severity, organ failure, thromboembolic events, mortality, and other blood parameters.
Results: The level of cfDNA, H3, NE, MPO, cfDNA-MPO complex, GAS6, and sAXL were all significantly increased in plasma of COVID-19 patients compared to controls. Importantly, a diminution of cfDNA and GAS6 levels over time was observed in patients surviving 30 days after ICU admission. Histone H3 levels were detected in 40% of the COVID-19 patient plasma at ICU admission and the presence of histone H3 during ICU stay was associated with an increased risk of thromboembolic events and secondary infection. Though NET markers were not predictive of 30-day mortality, they correlated with several parameters of tissue damage and neutrophil counts.
Summary/Conclusion: The increased presence of cfDNA, H3 and NE, MPO, and MPO-DNA illustrates the severity of cellular damage and indicates activation of NETosis in severe COVID-19 ICU patients. The evolution of cfDNA and Gas6 is able to predict disease prognosis of severely ill COVID-19 patients, where GAS6 appears to be part of an early activated mechanism in response to COVID-19. These data support treatment aimed at the reduction of NET formation in severe COVID-19 patients
Markers of NETosis and DAMPs are altered in critically ill COVID-19 patients
Background Coronavirus disease 19 (COVID-19) is known to present with disease severities of varying degree. In its most severe form, infection may lead to respiratory failure and multi-organ dysfunction. Here we study the levels of extracellular histone H3 (H3), neutrophil elastase (NE) and cfDNA in relation to other plasma parameters, including the immune modulators GAS6 and AXL, ICU scoring systems and mortality in patients with severe COVID-19.
Methods We measured plasma H3, NE, cfDNA, GAS6 and AXL concentration in plasma of 83 COVID-19-positive and 11 COVID-19-negative patients at admission to the Intensive Care Unit (ICU) at the Uppsala University hospital, a tertiary hospital in Sweden and a total of 333 samples obtained from these patients during the ICU-stay. We determined their correlation with disease severity, organ failure, mortality and other blood parameters.
Results H3, NE, cfDNA, GAS6 and AXL were increased in plasma of COVID-19 patients compared to controls. cfDNA and GAS6 decreased in time in in patients surviving to 30 days post ICU admission. Plasma H3 was a common feature of COVID-19 patients, detected in 40% of the patients at ICU admission. Although these measures were not predictive of the final outcome of the disease, they correlated well with parameters of tissue damage (H3 and cfDNA) and neutrophil counts (NE). A subset of samples displayed H3 processing, possibly due to proteolysis.
Conclusions Elevated H3 and cfDNA levels in COVID-19 patients illustrate the severity of the cellular damage observed in critically ill COVID-19 patients. The increase in NE indicates the important role of neutrophil response and the process of NETosis in the disease. GAS6 appears as part of an early activated mechanism of response in Covid-19.The study was supported through grants from the dedSciLifeLab/KAW national COVID-19 research
program project grant (MH), by Scilifelab, the Knut and Alice Wallenberg Foundation and in part by the
Swedish Research Council (RF, grant no 2014-02569 and 2014-07606), and the Netherlands Thrombosis
Foundation (GN).N
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