Non-linear 3-D Born shear waveform tomography in Southeast Asia

Background: Subjects with previous COVID-19 have augmented post-vaccination responses. However, the antibody response in COVID-naïve subjects from Southeast Asia is not well known. Methods: 77 COVID-naïve vaccinees were tested with a full antibody panel [spike antibodies (total (T-Ab), IgG, IgM) and neutralizing antibodies (N-Ab)] pre-vaccination, 10 days after dose 1, and 20/40/60/90/120/150/180 days after dose 2. Results: 10 days after dose 1, 67.6% (48/71)/69.0% (49/71) were T-Ab/IgG positive; only 15.5% (11/71)/14.1% (10/71) were N-Ab/IgM positive. While all (100%) subjects had brisk T-Ab, IgG and N-Ab antibody responses 20 days after complete vaccination, only 79.1% (53/67) were IgM positive. At 180 days (n = 8), T-Ab/IgG/N-Ab were still reactive (lowest T-Ab 186 U/mL, IgG 617 AU/mL, N-Ab 0.39 µg/mL), but IgM was negative in all samples. Spike antibody thresholds of T-Ab 74.1 U/mL (r = 0.95) and IgG 916 AU/mL (r = 0.95) corresponded to N-Ab reactivity (>0.3 µg/mL). Non-linear regression analysis showed that N-Ab would decrease to 0.3 µg/mL by 241 days, whereas T-Ab/IgG would need 470/163 days to reach titers of T-Ab/IgG associated with a N-Ab 0.3 µg/mL (76.4 U/mL and 916 AU/mL respectively). Conclusions: The antibody responses of T-Ab, IgG and N-Ab remain high and durable even at 180 days. N-Ab titers are expected to remain reactive up to 241 days post-vaccination.

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Towards 3D Multiscale Adjoint Waveform Tomography of the Lithosphere and Underlying Mantle beneath Southeast Asia

10.5194/egusphere-egu21-1586 ◽

2021 ◽

Author(s):

Deborah Wehner ◽

Nienke Blom ◽

Nicholas Rawlinson ◽

Meghan Miller ◽

Sri Widiyantoro ◽

...

Keyword(s):

Southeast Asia ◽

Velocity Structure ◽

Signal To Noise Ratio ◽

Data Availability ◽

Velocity Anomaly ◽

Seismic Waveform ◽

Path Coverage ◽

Gradient Based ◽

Waveform Tomography ◽

Window Selection

Southeast Asia is one of the most complex tectonic regions on Earth. This is mainly a result of its location within the triple junction of the Australian, Eurasian and Philippine Sea plates which has created a complicated configuration of active plate tectonic boundaries. Adjoint waveform tomography is especially suitable for imaging such complex regions. By simulating the 3D wavefield, it is possible to directly compare observed and simulated seismograms, thereby taking into account both body and surface waves. The method can account for the effects of anisotropy, anelasticity, wavefront healing, interference and (de)focusing that can hamper other seismological methods.To date, sparse instrument coverage in the region has contributed to a heterogeneous path coverage. In this project, we make use of publicly available data as well as our recently deployed networks of broadband seismometers on Borneo and Sulawesi. This, in addition to access to national permanent networks, provides data from over 300 stations which promises a significant improvement in data coverage around the Banda Arc, Borneo and Sulawesi. We employ a geographical weighting scheme to minimise the effect of dense regional arrays and compile a catalogue of 118&#160;well-constrained earthquakes, optimising for coverage, signal-to-noise ratio and data availability. An optimised window selection algorithm allows us to balance amplitude differences and include as much signal as possible while avoiding noisy data.Here, we present a seismic waveform tomography for upper mantle structure in Southeast Asia, imaging radially anisotropic S velocity, P velocity and density. We use a gradient-based optimisation scheme (L-BFGS) and adjoint methods to obtain sensitivity kernels as the corresponding gradients.&#160;In the first part of the inversion, periods down to 50 s are used to update a 1D initial model, adapting a multi-scale approach in which long periods are inverted for first to avoid cycle skipping.&#160;In our long-period results, we observe a strong&#160;regional low S-velocity structure with an underlying high-velocity anomaly. The&#160;results&#160;are&#160;consistent with the global&#160;S40RTS model.&#160;

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Towards 3D multiscale adjoint waveform tomography of the crust and upper mantle beneath Southeast Asia

10.5194/egusphere-egu2020-694 ◽

2020 ◽

Author(s):

Deborah Wehner ◽

Nienke Blom ◽

Nick Rawlinson

Keyword(s):

Southeast Asia ◽

Upper Mantle ◽

Signal To Noise Ratio ◽

Data Availability ◽

Tectonic Activity ◽

Initial Model ◽

Crust And Upper Mantle ◽

Banda Arc ◽

Waveform Tomography ◽

Krakatoa Eruption

Southeast Asia is one of the most complex tectonic regions on Earth. This is mainly a result of its location within the triple junction of the Australian, Eurasian and Philippine Sea plates which has created a complicated configuration of active plate tectonic boundaries. High plate velocities have generated thousands of kilometers of subducted material and ongoing subduction along the Sunda Arc represents a significant natural hazard (such as the 2004 Sumatra-Andaman earthquake, 2012 Indian Ocean earthquakes and 2018 Anak Krakatoa eruption). However, recent tectonic activity around Borneo may be related to postsubduction processes which could be the key to understanding how the tectonic subduction cycle terminates. Further east, the region is dominated by several minor tectonic plates and the spectacular 180-degree curvature of the Banda Arc. Our work aims to further improve the understanding of this area by providing detailed images of the upper mantle.Adjoint waveform tomography is especially suitable for imaging such complex regions. By simulating the 3D wavefield, it is possible to directly compare observed and simulated seismograms, thereby taking into account both body and surface waves. The method can account for the effects of anisotropy, anelasticity, wavefront healing, interference and (de)focusing that can hamper other seismological methods, and is thus especially suitable for strongly heterogenous areas such as Southeast Asia.To date, sparse instrument coverage in the region has contributed to a heterogeneous path coverage. In this project, we make use of publicly available data as well as our recently deployed networks of broadband seismometers on Borneo and Sulawesi. This, in addition to access to national permanent networks promises a significant improvement in data coverage around the Banda Arc, Borneo and Sulawesi, thereby providing new opportunities to untangle the region&#8217;s complexity.We compiled a catalogue of well-constrained earthquakes, optimising for coverage, signal-to-noise ratio and data availability across a wide frequency band, and compared our observed data to synthetics generated from an initial model. In the first part of the inversion, we use long periods of 100 - 150 s to update our initial model using a gradient-based optimisation scheme. We use adjoint methods to obtain sensitivity kernels as the corresponding gradients and initial results will be documented in this presentation. In subsequent iterations, we permit increasingly shorter periods in order to progressively recover finer scales structure and avoid cycle skipping issues.

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IS THERE A KUZNETS' PROCESS IN SOUTHEAST ASIA?

The Singapore Economic Review ◽

10.1142/s0217590815500174 ◽

2015 ◽

Vol 60 (02) ◽

pp. 1550017 ◽

Cited By ~ 1

Author(s):

ABDUL JABBAR ABDULLAH ◽

HRISTOS DOUCOULIAGOS ◽

ELIZABETH MANNING

Keyword(s):

Southeast Asia ◽

Kuznets Curve ◽

Linear Effect ◽

Agricultural Employment ◽

Non Linear ◽

Government Involvement ◽

Per Capita ◽

National Governments ◽

Robust Evidence

Relatively little is known about the determinants of inequality in Southeast Asia. This paper fills this void by comprehensively testing Kuznets' hypothesis for Southeast Asia. We estimate both unconditional and conditional Kuznets' curves using panel data for 8 countries. The analysis suggests the existence of a Kuznets' curve with respect to per capita income; the path of inequality is non-linear with respect to economic development. There is no evidence of a Kuznets curve with respect to non-agricultural employment. There is some evidence in terms of urbanization, though this is not robust. There is robust evidence on the role of national governments and education in shaping the path of inequality in the region. Government involvement reduces inequality. Education appears to have a non-linear effect on inequality.

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Waveform tomography in the Mediterranean and Southeast Asia

10.5194/egusphere-egu2020-967 ◽

2020 ◽

Author(s):

Nienke Blom ◽

Andreas Fichtner ◽

Alexey Gokhberg ◽

Nicholas Rawlinson ◽

Deborah Wehner

Keyword(s):

Southeast Asia ◽

Subduction Zones ◽

Deep Structure ◽

Source Parameters ◽

Seismic Inversion ◽

Earthquake Source Parameters ◽

North Borneo ◽

The World ◽

The Mediterranean ◽

Waveform Tomography

In this work, we present results from waveform tomography conducted in the Mediterranean and Southeast Asia. Whilst computationally more expensive than ray-based imaging methods, the advantage of waveform methods lies in their ability to incorporate in a consistent manner all the information contained in seismograms &#8211; not just the arrivals of certain, specified phases. We can therefore naturally and coherently exploit body and multimode surface waves, and take into account source effects, frequency-dependence, wavefront healing, anisotropy and attenuation.Here, we look at applications of this method in two geologically complex regions: the Mediterranean and Southeast Asia. Both are characterised by broadscale convergence and a complicated pattern of interactions between larger and smaller-scale tectonic plates.The Mediterranean is historically one of the best studied areas in the world, with an impressive density of seismic stations which greatly aids the detailed imaging of the region. We have been able to image the Central and Eastern Mediterranean down to the mantle transition zone, thereby illuminating the complex slab structures and geometries within the domain. We identify several main slabs that correspond to major current and former subduction zones.In Southeast Asia, we work at a larger scale, with a model domain encompassing the Sunda arc (which gives rise to some of the world&#8217;s most significant natural hazards), the Banda arc with its spectacular 180&#176; curvature and various smaller-scale features, such as the tectonically complex island of Sulawesi. To date, sparse instrument coverage in the region has led to a heterogeneous path coverage, in particular around Borneo which is located in an intra-plate setting. A recent series of temporary seismometer deployments in Sabah (North Borneo), Kalimantan, Sulawesi and the Celebes Sea allows us to fill the gaps in the publicly available data, thereby providing new opportunities to investigate the region's complexity using waveform tomography.In this presentation, we will also discuss a number of features and &#8220;best practices&#8221; that can significantly influence waveform tomography results. In particular, we highlight how we can optimise sensitivity to deep structure by combining long-period data with a window selection approach that specifically targets body wave signals, and we discuss the effect of uncertainties in earthquake source parameters on the seismic inversion process.

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SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography

10.1002/essoar.10507767.1 ◽

2021 ◽

Author(s):

Deborah Wehner ◽

Nienke Blom ◽

Nicholas Rawlinson ◽

Daryono Daryono ◽

Christian Boehm ◽

...

Keyword(s):

Southeast Asia ◽

Structural Model ◽

Multi Scale ◽

Waveform Tomography

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B. The Non-Linear Calculations for Pulsating Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900019008 ◽

1967 ◽

Vol 28 ◽

pp. 105-176

Author(s):

Robert F. Christy

Keyword(s):

Major Part ◽

Afternoon Session ◽

Discussion Session ◽

Pulsating Stars ◽

Fourth Symposium ◽

Non Linear ◽

Considerable Discussion ◽

Informal Approach ◽

Preceding Session

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)

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On The Possibility of an Autonomous History of Modern Southeast Asia

Journal of Southeast Asian History ◽

10.1017/s0084255900007944 ◽

1961 ◽

Vol 2 (2) ◽

pp. 73-105 ◽

Cited By ~ 2

Author(s):

John R. W. Small

Keyword(s):

Southeast Asia ◽

Contemporary History ◽

The Past ◽

History Of

It is generally accepted that history is an element of culture and the historian a member of society, thus, in Croce's aphorism, that the only true history is contemporary history. It follows from this that when there occur great changes in the contemporary scene, there must also be great changes in historiography, that the vision not merely of the present but also of the past must change.

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