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HKU Science Faculty website made a hat-trick by receiving its third international recognition – the W³ Silver Award

  New face of Faculty of Science website has just made a hat-trick by receiving the W³ Silver Award in the 14th Annual W3 Awards – its third recognition in international awards following its Award of Distinction at the 25th Annual Communicator Awards and University Standard of Excellence award at the WebAward 2019. The website is also recognised as a “Friendly Website” under the Web Accessibility Recognition Scheme (2018/19). The new Faculty website has a new face with global outlook by the smart use of graphically-impressive images and layout design. It simultaneously neatly presents all the text information and making it a user-friendly website and accessible for all stakeholders and general public. It allows readers easily search and acquire the content with a pleasant reading of the website with magazine-like style, at the same time demonstrating our commitment in teaching and research excellence, knowledge exchange, alumni networking and more. The W³ Awards celebrates digital excellence and is the first major web competition to be accessible to the biggest agencies, the smallest firms, and everyone in between. In its fourteenth year, the W³ Awards received over 5,000 entries. In determining winners, entries are judged based on a standard of excellence as determined by the Academy of Interactive and Visual Arts (AIVA), according to the category entered.

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Dr Ziyang Meng, HKU Department of Physics

Emmy Noether looks at the deconfined quantum critical point

A research team led by Dr Ziyang Meng from the Department of Physics has established an interesting connection between the classical Noether’s theorem in physics to the most modern quantum many-body research [1].   The German scientist Emmy Noether (1882 – 1935), perhaps the greatest female physicist and mathematician, has discovered an important theorem—Noether's theorem [2] —which relates symmetries with conservation laws. The theorem states that for every continuous symmetry generated by local actions, there corresponds a conservation law.   Applications of the theorem are everywhere in science, physics, chemistry, biology, such as the space-time translation symmetry gives rise to momentum-energy conservation, the rotation symmetry gives rise to angular momentum conservation, etc. However, over the years people turn to unconsciously relate the fundamental law of physics like Noether's theorem to classical and text-book examples, and rarely expect the immediate application of them in the frontier of research which is beyond any established paradigms.   In a recent research work [1], to one’s surprise, a team led by HKU physicist Dr Ziyang Meng establishes an interesting connection between the Noether’s theorem and the most modern quantum material research. In the work, Dr Ziyang Meng, Dr Nvsen Ma from the Institute of Physics, Chinese Academy of Sciences and Dr Yi-Zhuang You from University of California at San Diego, demonstrated an explicit application of the Noether's theorem in identifying the emergent continuous symmetry in an exotic quantum phase transition–the deconfined quantum critical point (DQCP), which is the quantum phase transition beyond the conventional paradigm of phases of matter. The work was published in the recent issue of Physical Review Letters. (link of the article).   Fig.1 Emmy Noether (1882 – 1935) was a German mathematician who made important contributions to abstract algebra and theoretical physics. She was described by Pavel Alexandrov, Albert Einstein, Jean Dieudonné, Hermann Weyl and Norbert Wiener as the most important woman in the history of mathematics. As one of the leading mathematicians of her time, she developed the theories of rings, fields, and algebras. In physics, Noether's theorem explains the connection between symmetry and conservation laws [2] (From Wikipedia). In the research work [1], a team lead by HKU physicist establishes an interesting connection between the Noether’s theorem and the most modern quantum material research.   In quantum many-body systems, the manifestation of symmetry can be much richer than that in their classical counterparts, new symmetry that does not exist in the microscopic model could emerge at low energy and lead to emergent conservation law. A great platform to test these ideas is the deconfined quantum critical point (DQCP). As schematically shown in Fig. 2, the DQCP is an exotic quantum critical point between two spontaneous symmetry breaking phases: the antiferromagnetic phase (AFM) and the valence bond solid (VBS) phase. Deconfined degrees of freedom, such as fractionalized spinons and emergent gauge fluctuations, appear at and only at DQCP. The fractionalization generally enlarges the scaling dimension of order parameters and makes other symmetry breaking terms irrelevant, which paves the way for larger symmetry to emerge.   Fig.2. Schematic plot of the phase diagram of J-Q model with AFM and VBS phases and the deconfined quantum critical point (DQCP). At the DQCP, spin excitation at the momentum point X=(pi,0) is the conserved current of the emergent O(4) symmetry, therefore its scaling dimension is an integer value only related with space-time dimension of the model, and such conservation is identified from quantum Monte Carlo simulations in Ref. [1].   The research team investigated the two dimensional easy-plane JQ model as shown in Fig.2. According to the Noether’s theorem, every continuous symmetry of a physical system is associated with a corresponding conservation law, the conservation law further manifests itself in the form of a conserved current. Therefore, the observation of a conserved current in a physical system is the direct evidence of the existence of the associated continuous symmetry. At the DQCP shown in Fig. 2, the generators of emergent O(4) symmetry rotate between the AFM and VBS order parameters, the detection of its associated conserved current (the AFM-VBS current) would provide strong support for the emergent symmetry and hence the field theory description of the DQCP.   To test the proposition, the team performed large-scale quantum Monte Carlo simulations. They measured the dynamical spin correlation functions at the corresponding momenta, and found that its scaling dimension is indeed converged to the integer only related with the space-time dimension of the problem – the unique property of conserved current operator – precisely consistent with the requirement of the conservation law. Therefore the simulation results in Ref. [1] confirm the emergent O(4) symmetry at DQCP by measuring the associated emergent conserved current in the spin excitation spectrum.This study demonstrated an elegant yet practical approach to detect emergent symmetry by probing the spin excitation, which could potentially guide the ongoing experimental search for DQCP in quantum magnets. Moreover, the idea of employing conserved current to detect the emergent continuous symmetry in quantum many-body systems has also inspired several recent works [3,4,5]. It was expected that the research would further motivate active search and future experimental detection of quantum magnets that belong to the materials in new paradigms of quantum matter.   Acknowledgement The large-scale simulations are performed on the Tianhe-1A platform at the National Supercomputer Center in Tianjin and Tianhe-2 platform at the National Supercomputer Center in Guangzhou, the authors acknowledge the technical support and generous allocation of CPU time from these centers. The authors also thank the funding support from the Ministry of Science and Technology of China through the National Key Research and Development Program (2016YFA0300502), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB28000000), the National Science Foundation of China (11574359,11674370) and the DFG research unit FOR1807 and Mercator Fellow.   The authors would like to thank the support from the “Computational Initiative – Towards Next-Generation Scientific Computing via Neuromorphic-AI Accelerators” at the Faculty of Science, the University of Hong Kong.   Journal Reference [1] Role of Noether’s Theorem at the Deconfined Quantum Critical Point, Nvsen Ma, Yi-Zhuang You, and Zi Yang Meng, Phys. Rev. Lett. 122, 175701 (2019), https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.175701   [2] Noether, Emmy (1918), "Invariante Variationsprobleme", Nachr. D. Koenig. Gesellsch. D. Wiss. Zu Goettingen, Math-phys. Klasse, 1918: 235–257 Translated in Noether, Emmy (1971). "Invariant variation problems". Transport Theory and Statistical Physics. 1 (3): 186. arXiv:physics/0503066. doi:10.1080/00411457108231446   [3] Quantum phases of SrCu2(BO3)2 from high-pressure thermodynamics, Jing Guo, Guangyu Sun, Bowen Zhao, Ling Wang, Wenshan Hong, Vladimir A. Sidorov, Nvsen Ma, Qi Wu, Shiliang Li, Zi Yang Meng, Anders W. Sandvik, Liling Sun, arXiv:1904.09927   [4] Emergent Symmetry and Conserved Current at a One Dimensional Incarnation of Deconfined Quantum Critical Point, Rui-Zhen Huang, Da-Chuan Lu, Yi-Zhuang You, Zi Yang Meng, Tao Xiang Phys. Rev. B 100, 125137 (2019) Editors' Suggestion   [5] Signatures of a Deconfined Phase Transition on the Shastry-Sutherland Lattice: Applications to Quantum Critical SrCu2(BO3)2, Jong Yeon Lee, Yi-Zhuang You, Subir Sachdev, Ashvin Vishwanath arXiv:1904.07266

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Professor Xuechen LI

HKU Chemist Professor Xuechen Li elected to the HK Young Academy of Sciences

Professor Xuechen Li has been recently elected to Hong Kong Young Academy of Sciences.   Professor Li is honoured for his achievements and contributions for his innovative basic studies and translation research. His research group pioneered the new methods and strategies for chemically synthesizing biologics including glycans and proteins which are inaccessible by other means. In addition, he has made significant contributions to the cyclic peptide-based antibiotics development, with completion of the total synthesis of daptomycin and teixobactin.   Professor Li received his PhD from Harvard University in 2007. After postdoctoral work at the Memorial Sloan Kettering Cancer Center in New York, he joined the Department of Chemistry in 2009, and was promoted to Associate Professor in 2014 and Professor in 2018. Professor Li was the recipient of Wuxi PharmaTech Life Science and Chemistry-Scholar Award (2014), Distinguished Faculty Award by Chinese-American Chemistry & Chemical Biology Professor Association (CAPA) (2016), Croucher Senior Research Fellowship (2017), Outstanding Researcher Award by the University of Hong Kong (2018), and the Rao Makineni Award by American Peptide Society (2019).   To learn more about Professor Li's research, please click here.   Professor Li and his teixobactin project-team

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HKU Science Faculty website made a hat-trick by receiving its third international recognition – the W³ Silver Award

  New face of Faculty of Science website has just made a hat-trick by receiving the W³ Silver Award in the 14th Annual W3 Awards – its third recognition in international awards following its Award of Distinction at the 25th Annual Communicator Awards and University Standard of Excellence award at the WebAward 2019. The website is also recognised as a “Friendly Website” under the Web Accessibility Recognition Scheme (2018/19). The new Faculty website has a new face with global outlook by the smart use of graphically-impressive images and layout design. It simultaneously neatly presents all the text information and making it a user-friendly website and accessible for all stakeholders and general public. It allows readers easily search and acquire the content with a pleasant reading of the website with magazine-like style, at the same time demonstrating our commitment in teaching and research excellence, knowledge exchange, alumni networking and more. The W³ Awards celebrates digital excellence and is the first major web competition to be accessible to the biggest agencies, the smallest firms, and everyone in between. In its fourteenth year, the W³ Awards received over 5,000 entries. In determining winners, entries are judged based on a standard of excellence as determined by the Academy of Interactive and Visual Arts (AIVA), according to the category entered.

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Dr Ziyang Meng, HKU Department of Physics

Emmy Noether looks at the deconfined quantum critical point

A research team led by Dr Ziyang Meng from the Department of Physics has established an interesting connection between the classical Noether’s theorem in physics to the most modern quantum many-body research [1].   The German scientist Emmy Noether (1882 – 1935), perhaps the greatest female physicist and mathematician, has discovered an important theorem—Noether's theorem [2] —which relates symmetries with conservation laws. The theorem states that for every continuous symmetry generated by local actions, there corresponds a conservation law.   Applications of the theorem are everywhere in science, physics, chemistry, biology, such as the space-time translation symmetry gives rise to momentum-energy conservation, the rotation symmetry gives rise to angular momentum conservation, etc. However, over the years people turn to unconsciously relate the fundamental law of physics like Noether's theorem to classical and text-book examples, and rarely expect the immediate application of them in the frontier of research which is beyond any established paradigms.   In a recent research work [1], to one’s surprise, a team led by HKU physicist Dr Ziyang Meng establishes an interesting connection between the Noether’s theorem and the most modern quantum material research. In the work, Dr Ziyang Meng, Dr Nvsen Ma from the Institute of Physics, Chinese Academy of Sciences and Dr Yi-Zhuang You from University of California at San Diego, demonstrated an explicit application of the Noether's theorem in identifying the emergent continuous symmetry in an exotic quantum phase transition–the deconfined quantum critical point (DQCP), which is the quantum phase transition beyond the conventional paradigm of phases of matter. The work was published in the recent issue of Physical Review Letters. (link of the article).   Fig.1 Emmy Noether (1882 – 1935) was a German mathematician who made important contributions to abstract algebra and theoretical physics. She was described by Pavel Alexandrov, Albert Einstein, Jean Dieudonné, Hermann Weyl and Norbert Wiener as the most important woman in the history of mathematics. As one of the leading mathematicians of her time, she developed the theories of rings, fields, and algebras. In physics, Noether's theorem explains the connection between symmetry and conservation laws [2] (From Wikipedia). In the research work [1], a team lead by HKU physicist establishes an interesting connection between the Noether’s theorem and the most modern quantum material research.   In quantum many-body systems, the manifestation of symmetry can be much richer than that in their classical counterparts, new symmetry that does not exist in the microscopic model could emerge at low energy and lead to emergent conservation law. A great platform to test these ideas is the deconfined quantum critical point (DQCP). As schematically shown in Fig. 2, the DQCP is an exotic quantum critical point between two spontaneous symmetry breaking phases: the antiferromagnetic phase (AFM) and the valence bond solid (VBS) phase. Deconfined degrees of freedom, such as fractionalized spinons and emergent gauge fluctuations, appear at and only at DQCP. The fractionalization generally enlarges the scaling dimension of order parameters and makes other symmetry breaking terms irrelevant, which paves the way for larger symmetry to emerge.   Fig.2. Schematic plot of the phase diagram of J-Q model with AFM and VBS phases and the deconfined quantum critical point (DQCP). At the DQCP, spin excitation at the momentum point X=(pi,0) is the conserved current of the emergent O(4) symmetry, therefore its scaling dimension is an integer value only related with space-time dimension of the model, and such conservation is identified from quantum Monte Carlo simulations in Ref. [1].   The research team investigated the two dimensional easy-plane JQ model as shown in Fig.2. According to the Noether’s theorem, every continuous symmetry of a physical system is associated with a corresponding conservation law, the conservation law further manifests itself in the form of a conserved current. Therefore, the observation of a conserved current in a physical system is the direct evidence of the existence of the associated continuous symmetry. At the DQCP shown in Fig. 2, the generators of emergent O(4) symmetry rotate between the AFM and VBS order parameters, the detection of its associated conserved current (the AFM-VBS current) would provide strong support for the emergent symmetry and hence the field theory description of the DQCP.   To test the proposition, the team performed large-scale quantum Monte Carlo simulations. They measured the dynamical spin correlation functions at the corresponding momenta, and found that its scaling dimension is indeed converged to the integer only related with the space-time dimension of the problem – the unique property of conserved current operator – precisely consistent with the requirement of the conservation law. Therefore the simulation results in Ref. [1] confirm the emergent O(4) symmetry at DQCP by measuring the associated emergent conserved current in the spin excitation spectrum.This study demonstrated an elegant yet practical approach to detect emergent symmetry by probing the spin excitation, which could potentially guide the ongoing experimental search for DQCP in quantum magnets. Moreover, the idea of employing conserved current to detect the emergent continuous symmetry in quantum many-body systems has also inspired several recent works [3,4,5]. It was expected that the research would further motivate active search and future experimental detection of quantum magnets that belong to the materials in new paradigms of quantum matter.   Acknowledgement The large-scale simulations are performed on the Tianhe-1A platform at the National Supercomputer Center in Tianjin and Tianhe-2 platform at the National Supercomputer Center in Guangzhou, the authors acknowledge the technical support and generous allocation of CPU time from these centers. The authors also thank the funding support from the Ministry of Science and Technology of China through the National Key Research and Development Program (2016YFA0300502), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB28000000), the National Science Foundation of China (11574359,11674370) and the DFG research unit FOR1807 and Mercator Fellow.   The authors would like to thank the support from the “Computational Initiative – Towards Next-Generation Scientific Computing via Neuromorphic-AI Accelerators” at the Faculty of Science, the University of Hong Kong.   Journal Reference [1] Role of Noether’s Theorem at the Deconfined Quantum Critical Point, Nvsen Ma, Yi-Zhuang You, and Zi Yang Meng, Phys. Rev. Lett. 122, 175701 (2019), https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.175701   [2] Noether, Emmy (1918), "Invariante Variationsprobleme", Nachr. D. Koenig. Gesellsch. D. Wiss. Zu Goettingen, Math-phys. Klasse, 1918: 235–257 Translated in Noether, Emmy (1971). "Invariant variation problems". Transport Theory and Statistical Physics. 1 (3): 186. arXiv:physics/0503066. doi:10.1080/00411457108231446   [3] Quantum phases of SrCu2(BO3)2 from high-pressure thermodynamics, Jing Guo, Guangyu Sun, Bowen Zhao, Ling Wang, Wenshan Hong, Vladimir A. Sidorov, Nvsen Ma, Qi Wu, Shiliang Li, Zi Yang Meng, Anders W. Sandvik, Liling Sun, arXiv:1904.09927   [4] Emergent Symmetry and Conserved Current at a One Dimensional Incarnation of Deconfined Quantum Critical Point, Rui-Zhen Huang, Da-Chuan Lu, Yi-Zhuang You, Zi Yang Meng, Tao Xiang Phys. Rev. B 100, 125137 (2019) Editors' Suggestion   [5] Signatures of a Deconfined Phase Transition on the Shastry-Sutherland Lattice: Applications to Quantum Critical SrCu2(BO3)2, Jong Yeon Lee, Yi-Zhuang You, Subir Sachdev, Ashvin Vishwanath arXiv:1904.07266

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Dr Xiang David Li (middle) with his collaborators Dr Karen Wing Yee Yuen (left) and Dr Jason Wing Hon Wong (right)

Decoding a new sign in chromatin maze: HKU chemical biologists identify a new histone mark that regulates chromatin structure during gene expression and DNA repair

A research team led by Dr Xiang David Li, Associate Professor from the Department of Chemistry, in collaboration with Dr Karen Wing Yee Yuen from the School of Biological Sciences and Dr Jason Wing Hon Wong from the School of Biomedical Sciences, revealed a new fundamental mechanism by which a cell can make necessary changes in its chromatin structure in response to different DNA-associated processes such as gene expression and DNA damage repair. The findings were recently published in the prestigious scientific journal Molecular Cell.   Imagine, for a moment, that you are now living in the centre of an ever-shifting maze: paths moving about and breaking apart, wide, straight roads curling up and shrinking into tight, winding tracks, new roads appearing from what used to be dead-ends. Travelling through this labyrinth, the only thing guiding you on the way is various road signs (e.g., “STOP”, “SLOW”, “ONE WAY” and “DO NOT ENTER”) that indicate whether and how you may traverse different paths.   One such maze lies within our every cell: the chromatin, in which DNA is packaged with proteins called histones. Packaging of DNA can be tighter or looser in different regions of chromatin. While a loose packaging indicates an “active” or a gene “ON” region, a tight compaction means a “silent” or a gene “OFF” region. Interestingly, the chromatin also contains various “road signs” in the form of chemical modifications to histones (or histone marks) that indicate the active, inactive or damaged regions of the chromatin and give order to various chromatin-associated machineries in the regulation of gene expression, DNA replication and damage repair. While some well-known chromatin ”road signs” such as lysine acetylation (Kac) and methylation (Kme) have been well characterised, the biological meanings of many other “signs”, particularly those newly identified histone marks, remain mysterious.   In a search for new chromatin “road sign”, Dr Li’s team discovered a novel histone mark, lysine glutarylation (Kglu) at histone H4, Lysine-91 (H4K91glu) from human cells. “I was so excited to find this new histone mark. Now imagine that in the maze you come across a new sign that you’ve not seen before. Who puts it there? What does it mean?” said Dr Xiucong Bao, a postdoctoral fellow in Dr Li’s lab and the first author of the study, but she also notes the great challenge to uncover these mysteries, for which she has spent more than five years on the project. The researchers finally found that this mark is especially abundant in promoter regions of active, “open” chromatin where genes are highly expressed – equivalent to a road sign in the maze showing “expressway”. “We believe that H4K91glu is a “sign” for activation of gene expression,” said Dr Li. “And this ‘sign’ seems to be conserved in evolution, as we found it in not only human but also mouse, fly, worm and even baker's yeast cells.”   Besides marking the active genomic region, H4K91glu in fact directly contributes to the formation of the more open accessible chromatin structure facilitating gene expression. Dr Li’s team found in this study that H4K91glu destabilizes nucleosome, the basic repeating unit of chromatin, and leads to activation or “opening” of chromatin. “It makes perfect sense if you know chemistry, as the mark puts a negative charge on an originally positively charged lysine residue. It therefore causes a charge-charge repulsion within the nucleosome and makes it more prone to falling apart,” says Dr Li.   Image 1. Chromatin maze with various histone modifications as “road signs”. Dr. Li’s team discovered a new histone modification, glutarylation at histone H4 lysine 91, that locates at ‘open’ chromatin where genes are highly expressed – equivalent to a road sign in the maze showing ‘expressway’.   Much like the ever-shifting maze, chromatin packaging is highly dynamic. A compacted region of chromatin at this moment can quickly change to a relaxed one at the next moment, which allows fast switching between gene ON and OFF states. Meanwhile, when chromatin structure is changed at a specific region, the old “road signs” (i.e., histone marks) are taken off and the new ones are installed by enzymes called histone mark “erasers” and “writers”, respectively. “To understand a histone mark, it is key to find its “writer” and “eraser”, says Li, whose team further identified the enzymes that “write” and “erase’”= the H4K91glu mark: KAT2A, working together with the α-ketoadipate dehydrogenase (α-KADH) complex, adds the H4K91glu mark, while SIRT7 works to remove it. The researchers went on to demonstrate that H4K91glu must be removed by SIRT7 such that the open chromatin region could be inactivated and condensed during cell division or at local DNA damage site.   In summary, Dr Li’s study identified H4K91glu as a novel histone mark and unraveled its regulation and function in chromatin structure and dynamics, putting us one step closer towards deciphering the yet mysterious chromatin maze. The findings from this study also laid the foundation for elucidating how this novel histone mark contributes to human health and disease and will open opportunities for development of therapeutic agents for the treatment of human diseases associated with mis-regulation of histone H4K91glu and chromatin structure.   This research is supported by General Research Fund, Collaborative Research Fund and the Area of Excellence Scheme from Hong Kong Research Grants Council, and the National Natural Science Foundation of China.   Click hereFor more information about the paper “Glutarylation of Histone H4 Lysine 91 Regulates Chromatin Dynamics” at Molecular Cell.   Click hereFor more information about Dr Xiang David Li and his research group.

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Professor Xuechen LI

HKU Chemist Professor Xuechen Li elected to the HK Young Academy of Sciences

Professor Xuechen Li has been recently elected to Hong Kong Young Academy of Sciences.   Professor Li is honoured for his achievements and contributions for his innovative basic studies and translation research. His research group pioneered the new methods and strategies for chemically synthesizing biologics including glycans and proteins which are inaccessible by other means. In addition, he has made significant contributions to the cyclic peptide-based antibiotics development, with completion of the total synthesis of daptomycin and teixobactin.   Professor Li received his PhD from Harvard University in 2007. After postdoctoral work at the Memorial Sloan Kettering Cancer Center in New York, he joined the Department of Chemistry in 2009, and was promoted to Associate Professor in 2014 and Professor in 2018. Professor Li was the recipient of Wuxi PharmaTech Life Science and Chemistry-Scholar Award (2014), Distinguished Faculty Award by Chinese-American Chemistry & Chemical Biology Professor Association (CAPA) (2016), Croucher Senior Research Fellowship (2017), Outstanding Researcher Award by the University of Hong Kong (2018), and the Rao Makineni Award by American Peptide Society (2019).   To learn more about Professor Li's research, please click here.   Professor Li and his teixobactin project-team

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A life reconstruction of the feathered dinosaur Anchiornis huxleyi.

What colour were fossil animals? HKU palaeontologists evaluate fossil colour reconstruction methods to propose new study framework

Dr Michael Pittman of the Vertebrate Palaeontology Laboratory, Department of Earth Sciencesled an international study with his PhD student Mr Arindam Roy that evaluates fossil colour reconstruction methods to propose a new study framework that improves and expands current practice. The paper was recently published in the journal Biological Reviews. “People are fascinated by the colour and pattern of dinosaurs and other extinct animals because these aspects can tell you so much about an animal. Just think of a zebra and a peacock. We evaluated everything we know about fossil and modern animal colour and used that knowledge to propose a framework to improve how we reconstruct fossil colour in the future.” said Dr Pittman. Colour and patterns are critical to understanding the life, ecology, physiology and behaviour of animals. These colours are produced when light interacts with pigments and the structure of animal tissue. Common naturally-occurring animal pigments include melanin, carotenoids, porphyrins pterins, flavins and psittacofulvins which produce colours ranging from black and grey to yellow, orange and green (Figure 1). Feathered dinosaur fossils instrumental to understanding the origin of birds were the first animal fossils to yield evidence of melanin, the colour pigment we also have in our eyes and hair (Figures 2, 3). In the last ten years, colour patterns have been reconstructed in over 30 fossil animals including birds, non-avialan dinosaurs and mammals, providing a unique opportunity to test ecological and behavioral hypotheses that were previously out of reach. Unfortunately, our knowledge of other pigments is scarce in the fossil record as these non-melanin pigments are more difficult to fossilise. This incomplete knowledge and the lack of a standard study approach have been prevailing challenges to the reconstruction of colour in fossil animals. Co-author Dr Evan Saitta of the Field Museum of Natural History, Chicago, USA said, “We are in the golden age of multidisciplinary techniques in palaeontology. This is the first comprehensive study that not only critically evaluates the currently available methods, but also provides a reliable and repeatable framework that covers all vertebrate pigment systems not just melanin alone.” The new palaeocolour reconstruction framework proposed by Dr Michael Pittman, Mr Arindam Roy and their international team (Figure 4) comprises four main steps: (1) Map the known or suspected extent of preserved colour and patterns in the specimen; (2) Search for pigment-bearing microstructures using electron microscopy e.g. microstructure shape can be used to identify melanin-based colours like black, grey and brown); (3) If melanin-based colours are not detected, use high-end chemical analysis techniques to detect biomarkers of other pigments (4) Use reconstructed colours and patterns to test fundamental hypotheses related to animal physiology, ecology and behaviour. The new framework overcomes past challenges by incorporating the chemical signatures of different pigments, large and small-scale anatomical details visible in fossils as well as the potential for different pigments to fossilise. This framework provides background context for the evolution of colour-producing mechanisms and is expected to encourage future efforts to reconstruct colour in more fossil animals including non-dinosaur reptiles and mammals. Mr Roy, the study’s first author and a Hong Kong PhD Fellow said, “I am really excited by the course we have charted in this review study as I will be tackling many of the key issues we identified during my PhD studies at HKU.” The paper: A Roy, M Pittman, E T Saitta, T G Kaye and X Xu. Recent advances in amniote palaeocolour reconstruction and a framework for future research. Biological Reviews.   Link to journal article   Figure 1. Distribution of different colour-producing pigments among vertebrate animals. Covers fishes, amphibians, mammals, lizards, snakes, crocodilians and extinct archosaurs including non-avialan dinosaurs and birds. Dotted lines indicate stem groups; bold lines indicate crown groups.   Figure 2. A pristine specimen of the feathered dinosaur Anchiornis huxleyi showing its colour patterns. Melanin was first identified from an animal from this species. Image Credit: Xiaoli Wang).   Figure 3. A life reconstruction of the feathered dinosaur Anchiornis huxleyi based on fossil evidence of its colour and patterning. This evidence included inferences about melanin pigments. Image credit: HKU MOOC / Julius T Csotonyi / Michael Pittman.   Figure 4. (A) New framework for reconstructing fossil colour in animals. Solid lines indicate confirmed steps; dashed lines indicate potentially useful steps that deserve further investigation. (B) Sediment-encased maturation is method of producing artificial fossils that helps to better understand how fossils are preserved. Abbreviations: ESI-MS, electrospray ionisation mass spectrometry; FIB-TEM, focused ion beam-transmission electron microscopy; FT-ICR-MS, Fourier-transform ion cyclotron resonance mass spectrometry; HPLC-MS, high performance liquid chromatography; LSF, Laser-Stimulated Fluorescence; MLR, multinomial logistic regression; NMR, nuclear magnetic resonance; PCA, principal components analysis; PPC, peak probability contrast; Py-GC-MS, pyrolysis-gas chromatography-mass spectroscopy; synchotron-LDPI, laser desorption-ionisation; TDCA, thiazole-4,5-dicarboxylic acid; TOF-SIMS, time of flight secondary-ion mass spectroscopy; UV, ultra-violet light.    

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Professor Luk Kam Biu at the Daya Bay Reactor Neutrino experiment

HKU Distinguished Visiting Professor Luk Kam Biu named laureate of prestigious China's Future Science Prize – China’s “Nobel Prize”

Professor Luk Kam Biu, Hung Hing Ying Distinguished Visiting Professor in Science and Technology, HKU Professor Luk Kam Biu, a Hung Hing Ying Distinguished Visiting Professor in Science and Technology and an alumnus of the Department of Physics at the University of Hong Kong, has been chosen as a laureate of China's 2019 Future Science Prize. Professor Luk is currently a Professor of the University of California at Berkeley and a Senior Faculty Scientist of the Lawrence Berkeley National Laboratory. The Future Science Prize is considered China's "Nobel Prize”. It is the first Chinese non-governmental science award jointly initiated by groups of scientists and entrepreneurs aiming at supporting original and innovative research in foundational science, and awarding scientists with splendid contributions in the Greater China Region. The Prize is given in three categories: Life Science Prize, Physical Science Prize, and Mathematics and Computer Science Prize. Four scientists are awarded this year. Professor Luk won the prize in physical sciences jointly with Professor Wang Yifang, director of the Institute for High-Energy Physics under the Chinese Academy of Sciences, for their leadership in the Daya Bay Reactor Neutrino experiment and contributions to the discovery of a new type of neutrino oscillation, which opens the door for new physics beyond the Standard Model of particle physics and holds the key for understanding the matter-antimatter asymmetry in the universe. The Daya Bay project, launched in 2003 and co-led by CUHK, HKU and 40 universities and research institutions, is a collaboration involving more than 200 scientists from five regions and countries. The Daya Bay experiment in 2012 produced the first definitive measurement of a non-zero value for the θ13 angle of the neutrino mixing matrix. This precise measurement consolidates the understanding of the neutrino oscillation and paves the way for future understanding of matter-antimatter asymmetry in the universe. Professor Luk said: “I feel really grateful for this prize. The remarkable achievements of the Daya Bay experiment are built upon the dedication and excellent teamwork of the entire collaboration. This honour truly belongs to all members. HKU has played a special role in this endeavor. It was through the first meeting held in the Physics Department at HKU that the Daya Bay project was launched. The generous support of the HKU administration during the early stage of the initiative undoubtedly seeded the success of the experiment. In addition, HKU has served as a hub for bridging the East and West in the collaboration by hosting meetings. Of course, the participation of faculty and students from HKU also made a difference.” HKU Vice-President (Research) Professor Andy Hor congratulated Professor Luk for the prestigious award. He said: “His prize is testimony of the importance of fundamental science (neutrino physics). It also inspires our people to investigate other areas of nuclear and high-energy physics and their potential applications in medicine, energy and environment. It further fuels the belief that if we are committed in advancing deep new knowledge, we won’t be too far from having a HK borne-and-bred Nobel Prize winner in HKU! We are also deeply grateful of the generous support of Hung Hing Ying and Leung Hau Ling Charitable Foundation which enables Professor Luk to visit and work with our young staff and students.” Professor Luk and collaborators’ work on neutrino oscillation received another international prestigious award in 2016 - the Breakthrough Prize in Fundamental Physics, in recognition of scientific advance. Using part of the Breakthrough prize, he has established the "Luk Kam-Biu Prize in Experimental Physics” in the HKU Department of Physics to encourage students to specialize in experimental physics which is underrepresented in Hong Kong.   A group photo of the research team taken during the Daya Bay experiment's collaboration meeting which took place at HKU in 2015. Professor Luk (7th person from right on front row)   Professor Luk (middle at back) and HKU members visited the Institute of Modern Physics, Chinese Academy of Sciences in Lanzhou earlier this year

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