91 research outputs found
A new absolute arrival time data set for Europe
The main aim of this study is to create a data set of accurate absolute arrival times for stations in Europe which do not report to the International Seismological Centre (ISC). Waveforms were obtained from data centres and temporary experiments and a semi-automatic picking method was applied to determine absolute arrival times for P and S phases. 85 000 arrival times were picked whose distribution of residuals shows generally low standard deviations on the order of 0.5-0.7 s. Furthermore, mean teleseismic station residuals reflect the properties of the underlying crust and uppermost mantle. Comparison to ISC data for matching event-station-phase combinations also confirms the good quality of the new absolute arrival time picks. Most importantly, this data set complements the ISC data as it fills regional data coverage gaps in Europ
Capacitance voltage curve simulations for different passivation parameters of dielectric layers on silicon
Surface passivation is a widely used technique to reduce the recombination losses at the semiconductor surface. The passivating layer performance can be mainly characterized by two parameters: The fixed charge density (Q ox) and the interface trap density (D it) which can be extracted from Capacitance-Voltage measurements (CV). In this paper, simulations of High-Frequency Capacitance-Voltage (HF-CV) curves were developed using simulated passivation parameters in order to examine the reliability of measured results. The D it was modelled by two different sets of functions: First, the sum of Gaussian functions representing different dangling bond types and exponential tails for strained bonds. Second, a simpler U-shape model represented by the sum of exponential tails and a constant value function was employed. These simulations were validated using experimental measurements of a reference sample based on silicon dioxide on crystalline silicon (SiO2/c-Si). Additionally, a fitting process of HF-CV curves was proposed using the simple U-shape D it model. A relative error of less than 0.4% was found comparing the average values between the approximated and the experimentally extracted D it's. The constant function of the approximated D it represents an average of the experimentally extracted D it for values around the midgap energy where the recombination efficiency is highest
Direct inversion of S-P differential arrival-times for Vp/Vs ratio in SE Asia
Open Access via Jisc Wiley agreementPeer reviewedPublisher PD
The Slab Puzzle of the AlpineâMediterranean Region: Insights from a new, HighâResolution, ShearâWave Velocity Model of the Upper Mantle
Mediterranean tectonics since the Lower Cretaceous has been characterized by a multiâphase subduction and collision history with temporally and spatiallyâvariable, smallâscale plate configurations. A new shearâwave velocity model of the Mediterranean upper mantle (MeRE2020), constrained by a very large set of over 200,000 broadband (8â350 s), interâstation, Rayleighâwave, phaseâvelocity curves, illuminates the complex structure and fragmentation of the subducting slabs. Phaseâvelocity maps computed using these measurements were inverted for depthâdependent, shearâwave velocities using a stochastic particleâswarmâoptimization algorithm (PSO). The resulting threeâdimensional (3âD) model makes possible an inventory of slab segments across the Mediterranean. Fourteen slab segments of 200â800 km length alongâstrike are identified. We distinguish three categories of subducted slabs: attached slabs reaching down to the bottom of the model; shallow slabs of shorter length in downâdip direction, terminating shallower than 300 km depth; and detached slab segments. The location of slab segments are consistent with and validated by the intermediateâdepth seismicity, where it is present. The new highâresolution tomography demonstrates the intricate relationships between slab fragmentation and the evolution of the relatively small and highly curved subduction zones and collisional orogens characteristic of the Mediterranean realm
Single-photon emission from InGaAs quantum dots grown on (111) GaAs
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 96, 093112 (2010) and may be found at https://doi.org/10.1063/1.3337097.In this letter, we demonstrate that self-organized InGaAs quantum dots (QDs) grown on GaAs (111) substrate using droplet epitaxy have great potential for the generation of entangled photon pairs. The QDs show spectrally sharp luminescence lines and low spatial density. A second order correlation value of g(2)(0)<0.3 proves single-photon emission. By comparing the power dependence of the luminescence from a number of QDs we identify a typical luminescence fingerprint. In polarization dependent microphotoluminescence studies a fine-structure splitting ranging â€40eV down to the determination limit of our setup (10eV) was observed.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement
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Spintronic Majority Gates
In this paper we present an overview of two types of majority gate devices based on spintronic phenomena. We compare the spin torque majority gate and the spin wave majority gate and describe work on these devices. We discuss operating conditions for the two device concepts, circuit implication and how these reflect on materials choices for device implementation
High Frequency of Endothelial Colony Forming Cells Marks a Non-Active Myeloproliferative Neoplasm with High Risk of Splanchnic Vein Thrombosis
Increased mobilization of circulating endothelial progenitor cells may represent a new biological hallmark of myeloproliferative neoplasms. We measured circulating endothelial colony forming cells (ECFCs) in 106 patients with primary myelofibrosis, fibrotic stage, 49 with prefibrotic myelofibrosis, 59 with essential thrombocythemia or polycythemia vera, and 43 normal controls. Levels of ECFC frequency for patient's characteristics were estimated by using logistic regression in univariate and multivariate setting. The sensitivity, specificity, likelihood ratios, and positive predictive value of increased ECFC frequency were calculated for the significantly associated characteristics. Increased frequency of ECFCs resulted independently associated with history of splanchnic vein thrombosis (adjusted odds ratioâ=â6.61, 95% CIâ=â2.54â17.16), and a summary measure of non-active disease, i.e. hemoglobin of 13.8 g/dL or lower, white blood cells count of 7.8Ă109/L or lower, and platelet count of 400Ă109/L or lower (adjusted odds ratioâ=â4.43, 95% CIâ=â1.45â13.49) Thirteen patients with splanchnic vein thrombosis non associated with myeloproliferative neoplasms were recruited as controls. We excluded a causal role of splanchnic vein thrombosis in ECFCs increase, since no control had elevated ECFCs. We concluded that increased frequency of ECFCs represents the biological hallmark of a non-active myeloproliferative neoplasm with high risk of splanchnic vein thrombosis. The recognition of this disease category copes with the phenotypic mimicry of myeloproliferative neoplasms. Due to inherent performance limitations of ECFCs assay, there is an urgent need to arrive to an acceptable standardization of ECFC assessment
Role of dietary fatty acids in mammary gland development and breast cancer
Breast cancer is the most common cancer among women worldwide. Estimates suggest up to 35% of cases may be preventable through diet and lifestyle modification. Growing research on the role of fats in human health suggests that early exposure in life to specific fatty acids, when tissues are particularly sensitive to their environment, can have long-term health impacts. The present review examines the role of dietary fat in mammary gland development and breast cancer throughout the lifecycle. Overall, n-3 polyunsaturated fatty acids have promising cancer-preventive effects when introduced early in life, and warrant further research to elucidate the mechanisms of action
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