264 research outputs found
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Modeling the large runup along a narrow segment of the Kaikoura coast, New Zealand following the November 2016 tsunami from a potential landslide
Appendix A. Supplementary data:
The following is the Supplementary data to this article: Download Word document (https://ars.els-cdn.com/content/image/1-s2.0-S0029801818318286-mmc1.docx - 3MB).Copyright © 2019 The Authors. The 2016 Mw 7.8 Kaikoura earthquake and consequent tsunami have been controversial because of uncertainty over whether and where the plate interface ruptured and the incapability of the proposed source models to reproduce the near-field runup of 7 m. Existing models identify a wide range of locations for the interface rupture, from on land to offshore, and fail to reproduce runup of 7 m near Kaikoura. To generate the large tsunami peak in Kaikoura tide gauge record and the observed runup height, offshore seafloor movement is necessary, but the offshore extension of the plate-interface rupture and its type, either seismic rupture or a landslide, is uncertain. Here, we propose a submarine landslide in addition to the earthquake source, with the landslide delayed 10–20 min after the earthquake rupture. The landslide volume is 4.5–5.2 km3, located within 173.7–174.3oE (longitude) and 42.6–42.15oS (latitude). Our proposed dual tsunami source successfully reproduces near-field tide gauge records as well as observed near-field runup height of 7 m. We showed that more accurate source models of earthquakes can be achieved by considering observed runup data through runup inversions in addition to waveform inversions.Brunel Research Initiative and Enterprise Fund 2017/18 (BUL BRIEF) at Brunel University Londo
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Numerical modeling of the subaerial landslide source of the 22 December 2018 Anak Krakatoa volcanic tsunami, Indonesia
The eruption of the Anak Krakatoa volcano (Indonesia) in December 2018 produced a destructive tsunami with maximum runup of 13 m killing 437 people. Since the occurrence of this rare tsunami, it has been a challenge as how to model this tsunami and to reconstruct the network of coastal observations. Here, we apply a combination of qualitative physical modeling and wavelet analyses of the tsunami as well as numerical modeling to propose a source model. Physical modeling of a volcano flank collapse showed that the initial tsunami wave mostly involves a pure-elevation wave. We identified initial tsunami period of 6.3–8.9 min through Wavelet analysis, leading to an initial tsunami dimension of 1.8–7.4 km. Twelve source models were numerically modelled with source dimensions of 1.5–4 km and initial tsunami amplitudes of 10–200 m. Based on the qualities of spectral and amplitude fits between observations and simulations, we constrained the tsunami source dimension and initial amplitude in the ranges of 1.5–2.5 km and 100–150 m, respectively. Our best source model involves potential energy of 7.14 × 1013–1.05 × 1014 J equivalent to an earthquake of magnitude 6.0–6.1. The amplitude of the final source model is consistent with the predictions obtained from published empirical equations.Royal Society, Great Britain Sasakawa Foundatio
High-resolution resonant inelastic x-ray scattering study of the electron-phonon coupling in honeycomb α-Li₂IrO₃
The excitations in honeycomb
α
−
Li
2
IrO
3
have been investigated with high-resolution resonant inelastic x-ray scattering (RIXS) at the O
K
edge. The low-energy response is dominated by a fully resolved ladder of excitations, which we interpret as being due to multiphonon processes in the presence of strong electron-phonon coupling (EPC). At higher energies, the orbital excitations are shown to be dressed by phonons. The high quality of the data permits a quantitative test of the analytical model for the RIXS cross section, which has been proposed to describe EPC in transition-metal oxides (TMOs). We find that the magnitude of the EPC is comparable to that found for a range of
3
d
TMOs. This indicates that EPC may be of equal importance in determining the phenomenology displayed by corresponding
5
d
-based systems
Elucidating colorectal cancer-associated bacteria through profiling of minimally perturbed tissue-associated microbiota
Sequencing-based interrogation of gut microbiota is a valuable approach for detecting microbes associated with colorectal cancer (CRC); however, such studies are often confounded by the effect of bowel preparation. In this study, we evaluated the viability of identifying CRC-associated mucosal bacteria through centimeter-scale profiling of the microbiota in tumors and adjacent noncancerous tissue from eleven patients who underwent colonic resection without preoperative bowel preparation. High-throughput 16S rRNA gene sequencing revealed that differences between on- and off-tumor microbiota varied considerably among patients. For some patients, phylotypes affiliated with genera previously implicated in colorectal carcinogenesis, as well as genera with less well-understood roles in CRC, were enriched in tumor tissue, whereas for other patients, on- and off-tumor microbiota were very similar. Notably, the enrichment of phylotypes in tumor-associated mucosa was highly localized and no longer apparent even a few centimeters away from the tumor. Through short-term liquid culturing and metagenomics, we further generated more than one-hundred metagenome-assembled genomes, several representing bacteria that were enriched in on-tumor samples. This is one of the first studies to analyze largely unperturbed mucosal microbiota in tissue samples from the resected colons of unprepped CRC patients. Future studies with larger cohorts are expected to clarify the causes and consequences of the observed variability in the emergence of tumor-localized microbiota among patients
Cigarette smoking, cytochrome P4501A1 polymorphisms, and breast cancer among African-American and white women
INTRODUCTION: Previous epidemiologic studies suggest that women with variant cytochrome P4501A1 (CYP1A1) genotypes who smoke cigarettes are at increased risk for breast cancer. METHODS: We evaluated the association of breast cancer with CYP1A1 polymorphisms and cigarette smoking in a population-based, case–control study of invasive breast cancer in North Carolina. The study population consisted of 688 cases (271 African Americans and 417 whites) and 702 controls (285 African Americans and 417 whites). Four polymorphisms in CYP1A1 were genotyped using PCR/restriction fragment length polymorphism analysis: M1 (also known as CYP1A1*2A), M2 (CYP1A1*2C), M3 (CYP1A1*3), and M4 (CYP1A1*4) RESULTS: No associations were observed for CYP1A1 variant alleles and breast cancer, ignoring smoking. Among women who smoked for longer than 20 years, a modest positive association was found among women with one or more M1 alleles (odds ratio [OR] = 2.1, 95% confidence interval [CI] = 1.2–3.5) but not among women with non-M1 alleles (OR = 1.2, 95% CI = 0.9–1.6). Odds ratios for smoking longer than 20 years were higher among African-American women with one or more M3 alleles (OR = 2.5, 95% CI = 0.9–7.1) compared with women with non-M3 alleles (OR = 1.3, 95% CI = 0.8–2.2). ORs for smoking in white women did not differ appreciably based upon M2 or M4 genotypes. CONCLUSIONS: Cigarette smoking increases breast cancer risk in women with CYP1A1 M1 variant genotypes and in African-American women with CYP1A1 M3 variant genotypes, but the modifying effects of the CYP1A1 genotype are quite weak
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