| 1. |
- Patterson, Nick, et al.
(author)
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Large-scale migration into Britain during the Middle to Late Bronze Age
- 2022
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In: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; , s. 588-594
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Journal article (peer-reviewed)abstract
- Present-day people from England and Wales harbour more ancestry derived from Early European Farmers (EEF) than people of the Early Bronze Age1. To understand this, we generated genome-wide data from 793 individuals, increasing data from the Middle to Late Bronze and Iron Age in Britain by 12-fold, and Western and Central Europe by 3.5-fold. Between 1000 and 875 BC, EEF ancestry increased in southern Britain (England and Wales) but not northern Britain (Scotland) due to incorporation of migrants who arrived at this time and over previous centuries, and who were genetically most similar to ancient individuals from France. These migrants contributed about half the ancestry of Iron Age people of England and Wales, thereby creating a plausible vector for the spread of early Celtic languages into Britain. These patterns are part of a broader trend of EEF ancestry becoming more similar across central and western Europe in the Middle to Late Bronze Age, coincident with archaeological evidence of intensified cultural exchange2-6. There was comparatively less gene flow from continental Europe during the Iron Age, and Britain's independent genetic trajectory is also reflected in the rise of the allele conferring lactase persistence to ~50% by this time compared to ~7% in central Europe where it rose rapidly in frequency only a millennium later. This suggests that dairy products were used in qualitatively different ways in Britain and in central Europe over this period.
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| 2. |
- Chen, Han, et al.
(author)
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LTBP-2 confers pleiotropic suppression and promotes dormancy in a growth factor permissive microenvironment in nasopharyngeal carcinoma
- 2012
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In: Cancer Letters. - : Elsevier. - 0304-3835 .- 1872-7980. ; 325:1, s. 89-98
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Journal article (peer-reviewed)abstract
- This study identified LTBP-2 as a pleiotropic tumor suppressor in nasopharyngeal carcinoma, which safeguards against critical malignant behaviors of tumor cells. LTBP-2 expression was significantly decreased or lost in up to 100% of NPC cell lines (7/7) and 80% of biopsies (24/30). Promoter hypermethylation was found to be involved in LTBP-2 silencing. Using a tetracycline-regulated inducible expression system, we unveiled functional roles of LTBP-2 in suppressing colony formation, anchorage-independent growth, cell migration, angiogenesis, VEGF secretion, and tumorigenicity. Three-dimensional culture studies suggested the involvement of LTBP-2 in maintenance of tumor cell dormancy in a growth factor favorable microenvironment.
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| 3. |
- Hsiao, Tiger Yu-Yang, et al.
(author)
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JWST Reveals a Possible z similar to 11 Galaxy Merger in Triply Lensed MACS0647-JD
- 2023
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 949:2
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Journal article (peer-reviewed)abstract
- MACS0647-JD is a triply lensed z similar to 11 galaxy originally discovered with the Hubble Space Telescope. The three lensed images are magnified by factors of similar to 8, 5, and 2 to AB mag 25.1, 25.6, and 26.6 at 3.5 mu m. The brightest is over a magnitude brighter than other galaxies recently discovered at similar redshifts z > 10 with JWST. Here, we report new JWST imaging that clearly resolves MACS0647-JD as having two components that are either merging galaxies or stellar complexes within a single galaxy. The brighter larger component "A" is intrinsically very blue (ss similar to-2.6 +/- 0.1), likely due to very recent star formation and no dust, and is spatially extended with an effective radius similar to 70 +/- 24 pc. The smaller component "B" (r similar to 20-+ 58 pc) appears redder (ss similar to-2 +/- 0.2), likely because it is older (100-200 Myr) with mild dust extinction (AV similar to 0.1 mag). With an estimated stellar mass ratio of roughly 2:1 and physical projected separation similar to 400 pc, we may be witnessing a galaxy merger 430 million years after the Big Bang. We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be dissimilar, which is also suggested by the spectral energy distribution fitting, suggesting they formed further apart. We also identify a candidate companion galaxy "C" similar to 3 kpc away, likely destined to merge with A and B. Upcoming JWST Near Infrared Spectrograph observations planned for 2023 January will deliver spectroscopic redshifts and more physical properties for these tiny magnified distant galaxies observed in the early universe.
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| 4. |
- Zeiger, Paul Michel, 1994-
(author)
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Modeling Vibrational Electron Energy Loss Spectroscopy with the Frequency-Resolved Frozen Phonon Multislice Method
- 2024
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Doctoral thesis (other academic/artistic)abstract
- Aberration correctors, improved monochromators, and better detectors have enabled exciting research with nanometer- and Ångstrom-scale resolution in the Scanning Transmission Electron Microscope (STEM). However the interaction of high-energy electrons with the many-body system of the sample is quite complex and hinders interpretation of experiments. Therefore measurements often need to be informed by extensive modeling of the beam-sample interaction.In this thesis, we report the development of a model for the computer simulation of vibrational Electron Energy Loss Spectroscopy (EELS) in the STEM, which we call the Frequency Resolved Frozen Phonon Multislice (FRFPMS) method. We motivate the development of the method by reviewing the field of vibrational EELS from the instrumental advances, which enabled it, over experimental progress to a detailed consideration of other theories of vibrational EELS. In the process, we identify the need for a method, which is able to take into account many of the complicating factors of the scattering process, such as multiple elastic interactions, and is computationally feasible today, even for extended structure models.After a brief overview of necessary computational methods, we showcase that the FRFPMS method satisfies this need by discussing several papers we have published on the method. We demonstrate that the FRFPMS method produces results, which agree very well with published experimental and also theoretical results, both for momentum-resolved as well as high spatial resolution vibrational EELS. Furthermore we compare the FRFPMS method with the Quantum Excitations of Phonons model and the first-order Born approximation for a simple model system. The FRFPMS method matches the predictions of the other theories provided that two small modifications are introduced, which modify the temperature and energy-loss dependent scaling as well as the large momentum-transfer behavior of the modelled cross section.We then apply such revised FRFPMS method to simulations of shifts of optical phonon frequencies in hBN as a function of isotopic composition. The FRFPMS results are in very good agreement with experiments performed by collaborators, demonstrating that vibrational EELS is capable of detecting such isotopic shift of phonon frequencies in a momentum-resolved fashion. In another application of our method we focus on simulating atomically-resolved STEM-EELS experiments on SrTiO3, which allow to interpret a subtle asymmetry in experimental large detector off-axis vibrational STEM-EELS maps as result of sensitivity to the direction of the phonon eigenvector. This enables imaging of anisotropic displacements of atoms as a function of vibrational frequency.
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