Alexander Kolpakov and Sinai Robins
Math. Comp. 89 (2019), 2031-2046.
Abstract, references and article information

Maria Bras-Amorós and Julio Fernández-González
Math. Comp. 89 (2020), 2017-2030.
Abstract, references and article information

George C. Linderman and Stefan Steinerberger
Math. Comp. 89 (2020), 1933-1952.
Abstract, references and article information

Shukai Du and Francisco-Javier Sayas
Math. Comp. 89 (2019), 1745-1782.
Abstract, references and article information

Mohamed Jleli, Bessem Samet and Philippe Souplet
Proc. Amer. Math. Soc. 148 (2020), 2579-2593.
Abstract, references and article information

Bin Li and Jieqiong Shen
Proc. Amer. Math. Soc. 148 (2020), 2565-2578.
Abstract, references and article information

Moacir Aloisio, Silas L. Carvalho and César R. de Oliveira
Proc. Amer. Math. Soc. 148 (2020), 2509-2523.
Abstract, references and article information

Joseph Reid
Proc. Amer. Math. Soc. 148 (2020), 2331-2343.
Abstract, references and article information

About 200 archaeological Song-Yuan period finds unearthed at Kai Tak will go on display in an exhibition at the Heritage Discovery Centre from tomorrow until February 26.

Following the closure of Kai Tak Airport in 1998, the planning work for the Kai Tak Development Area created opportunities for archaeological studies around the former Sacred Hill in Kowloon Bay.

An abundance of Song-Yuan period cultural remains were subsequently unearthed, including a huge amount of ceramics produced by various kilns in Zhejiang, Fujian and Jiangxi.

Similar products from the same period were exported widely and could be found in shipwrecks along the maritime ceramics route.

Highlights of the Treasures from the Sacred Hill: Song-Yuan Period Archaeological Discoveries from Kai Tak exhibition include green glazed incense burners with an eight trigrams pattern and a green glazed dish with a moulded double fish pattern produced by Longquan Kiln.

Other highlights include a brown glazed dragon jar with lugs and a green glazed basin with a phoenix pattern produced by Cizao Kiln and a Daguan Tongbao bronze coin.

Ceramics from the same period on loan from the Art Museum of the Chinese University of Hong Kong will also be displayed.

Curated by the Antiquities & Monuments Office, admission to the exhibition is free.

Call 2208 4400 for details.

The Space Museum is staging a special exhibition 2020 Astronomical Events to highlight six major astronomical events happening this year.

The events include grouping of the four planets with the moon in late March, the serial phenomena of Jupiter's moons on June 11 and 12, and the partial solar eclipse on June 21.

Information on the Perseid meteor shower in mid-August, the Geminid meteor shower in mid-December and the Jupiter-Saturn conjunction on December 21 will also be featured.

The exhibit explains details and phenomena of these events, while serving as a practical guide to help visitors pick the best dates, times, locations and tools to observe them.

It will run until September 21 in two phases. The first three events will be presented during the first phase from January to June, while the second phase events will be shown from June to September.

Admission is free.

Call 2721 0226 for enquiries.

Beatrice K. Gandara
Nov 1, 2011; 24:199-205
From Research to Practice

Carla E. Cox
Aug 1, 2017; 30:157-160
From Research to Practice

Samuel Dagogo-Jack
Jan 1, 2002; 15:
Articles

The 2020 Mathematical Art Exhibition Awards were made at the Joint Mathematics Meetings last week "for aesthetically pleasing works that combine mathematics and art." The chosen works were selected from the exhibition of juried works in various media by over 90 mathematicians and artists from around the world.

"Suspended Helical Stair," by Mark Donohue (California College of the Arts, San Francisco, CA), was awarded Best textile, sculpture, or other medium. "A unique cable system to suspend a stair was developed in collaboration with a leading structural engineer. The suspended cables form a double helicoid nested within an ascending spiral hyperboloid to create the necessary points of support for the gravity loads and lateral bracing for the seismic loads. Each concrete stair tread was designed as an independent element that is strung together with the stairs above and below it to form a single spiral stair when the steel cables that run through them are post tensioned. The entire stair tread and suspension cable system can be understood as a play of ruled surfaces with each part related to the other through their shared geometric lineage." The work is string and plywood,45 x 23 x 23 cm, 2018.

2018

"A Unit Domino," by Douglas McKenna (Mathemaesthetics, Inc., Boulder, CO), was awarded Best photograph, painting, or print. "This piece is based upon an artist-discovered "half-domino" space-filling curve. The drawing comprises some half-million connected line segments, arranged in two perfectly recursive levels of double-spiral pairs, slowly changing color, in a single, over-one-mile-long self-avoiding path from lower left to lower right (the lower right square that sticks out is an integral part of its self-negative structure). The limiting curve covers a self-similar gasket tile with an infinitely long, almost-everywhere linear border. With an upside-down copy of itself, two such gaskets of unit area exactly cover a 1x2 domino, without overlap. The artist's app/eBook "Hilbert Curves" for iPad/iPhone explains how he discovered these beautiful constructions." The work is a glicée print,106 x 66 cm, 2015.

"Computational Wings," by David Bachman (Pitzer College, Claremont, CA), received Honorable Mention. "The body of this dragonfly is taken from a photograph, while the wings were computationally generated. A variety of algorithms were used to create them. First, a set of points were randomly populated across each wing and moved by a circle packing algorithm, where the radius of each circle was inversely proportional to the distance from the body. Next, those points were used to create a Voronoi diagram. Main veins were located by a shortest walk algorithm through the edges of this diagram, and those veins were given a variable thickness according to the distance travelled as you traverse them outward from the body." The work is laser etched acrylic, 23 x 35 x 3 cm, 2019.

(Click on the thumbnails to see larger versions of the images.)

The Mathematical Art Exhibition Award "for aesthetically pleasing works that combine mathematics and art" was established in 2008 through an endowment provided to the American Mathematical Society by an anonymous donor who wishes to acknowledge those whose works demonstrate the beauty and elegance of mathematics expressed in a visual art form. The awards are $400 for Best photograph, painting, or print; $400 for Best textile, sculpture, or other medium; and $200 for Honorable Mention. The Mathematical Art Exhibition of juried works in various media is held at the annual Joint Mathematics Meetings of the American Mathematical Society (AMS) and Mathematical Association of America (MAA). a gallery of works in the 2020 exhibition will be on AMS Mathematical Imagery.

Find out more about the Mathematical Art Exhibition Award and see past recipients.

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The American Mathematical Society is dedicated to advancing research and connecting the diverse global mathematical community through our publications, meetings and conferences, MathSciNet, professional services, advocacy, and awareness programs.

Telomeres are specific nucleoprotein structures that are located at the ends of linear eukaryotic chromosomes and play crucial roles in genomic stability. Telomere DNA consists of simple repeats of a short G-rich sequence: TTAGGG in mammals and TTTAGGG in most plants. In recent years, the mammalian telomeric G-rich repeats have been shown to form G-quadruplex (G4) structures, which are crucial for modulating telomere functions. Surprisingly, even though plant telomeres are essential for plant growth, development, and environmental adaptions, only few reports exist on plant telomeric G4 DNA (pTG4). Here, using bulk and single-molecule assays, including CD spectroscopy, and single-molecule FRET approaches, we comprehensively characterized the structure and dynamics of a typical plant telomeric sequence, d[GGG(TTTAGGG)3]. We found that this sequence can fold into mixed G4s in potassium, including parallel and antiparallel structures. We also directly detected intermediate dynamic transitions, including G-hairpin, parallel G-triplex, and antiparallel G-triplex structures. Moreover, we observed that pTG4 is unfolded by the AtRecQ2 helicase but not by AtRecQ3. The results of our work shed light on our understanding about the existence, topological structures, stability, intermediates, unwinding, and functions of pTG4.

Pyruvate kinase muscle isoform 2 (PKM2) is a key glycolytic enzyme involved in ATP generation and critical for cancer metabolism. PKM2 is expressed in many human cancers and is regulated by complex mechanisms that promote tumor growth and proliferation. Therefore, it is considered an attractive therapeutic target for modulating tumor metabolism. Various stimuli allosterically regulate PKM2 by cycling it between highly active and less active states. Several small molecules activate PKM2 by binding to its intersubunit interface. Serine and cysteine serve as an activator and inhibitor of PKM2, respectively, by binding to its amino acid (AA)-binding pocket, which therefore represents a potential druggable site. Despite binding similarly to PKM2, how cysteine and serine differentially regulate this enzyme remains elusive. Using kinetic analyses, fluorescence binding, X-ray crystallography, and gel filtration experiments with asparagine, aspartate, and valine as PKM2 ligands, we examined whether the differences in the side-chain polarity of these AAs trigger distinct allosteric responses in PKM2. We found that Asn (polar) and Asp (charged) activate PKM2 and that Val (hydrophobic) inhibits it. The results also indicate that both Asn and Asp can restore the activity of Val-inhibited PKM2. AA-bound crystal structures of PKM2 displayed distinctive interactions within the binding pocket, causing unique allosteric effects in the enzyme. These structure-function analyses of AA-mediated PKM2 regulation shed light on the chemical requirements in the development of mechanism-based small-molecule modulators targeting the AA-binding pocket of PKM2 and provide broader insights into the regulatory mechanisms of complex allosteric enzymes.

Actinobacillus pleuropneumoniae (App) is the etiological agent of acute porcine pneumonia and responsible for severe economic losses worldwide. The capsule polymer of App serotype 1 (App1) consists of [4)-GlcNAc-β(1,6)-Gal-α-1-(PO4-] repeating units that are O-acetylated at O-6 of the GlcNAc. It is a major virulence factor and was used in previous studies in the successful generation of an experimental glycoconjugate vaccine. However, the application of glycoconjugate vaccines in the animal health sector is limited, presumably because of the high costs associated with harvesting the polymer from pathogen culture. Consequently, here we exploited the capsule polymerase Cps1B of App1 as an in vitro synthesis tool and an alternative for capsule polymer provision. Cps1B consists of two catalytic domains, as well as a domain rich in tetratricopeptide repeats (TPRs). We compared the elongation mechanism of Cps1B with that of a ΔTPR truncation (Cps1B-ΔTPR). Interestingly, the product profiles displayed by Cps1B suggested processive elongation of the nascent polymer, whereas Cps1B-ΔTPR appeared to work in a more distributive manner. The dispersity of the synthesized products could be reduced by generating single-action transferases and immobilizing them on individual columns, separating the two catalytic activities. Furthermore, we identified the O-acetyltransferase Cps1D of App1 and used it to modify the polymers produced by Cps1B. Two-dimensional NMR analyses of the products revealed O-acetylation levels identical to those of polymer harvested from App1 culture supernatants. In conclusion, we have established a protocol for the pathogen-free in vitro synthesis of tailored, nature-identical App1 capsule polymers.

Hippo pathway signaling limits cell growth and proliferation and maintains the stem-cell niche. These cellular events result from the coordinated activity of a core kinase cassette that is regulated, in part, by interactions involving Hippo, Salvador, and dRassF. These interactions are mediated by a conserved coiled-coil domain, termed SARAH, in each of these proteins. SARAH domain–mediated homodimerization of Hippo kinase leads to autophosphorylation and activation. Paradoxically, SARAH domain–mediated heterodimerization between Hippo and Salvador enhances Hippo kinase activity in cells, whereas complex formation with dRassF inhibits it. To better understand the mechanism by which each complex distinctly modulates Hippo kinase and pathway activity, here we biophysically characterized the entire suite of SARAH domain–mediated complexes. We purified the three SARAH domains from Drosophila melanogaster and performed an unbiased pulldown assay to identify all possible interactions, revealing that isolated SARAH domains are sufficient to recapitulate the cellular assemblies and that Hippo is a universal binding partner. Additionally, we found that the Salvador SARAH domain homodimerizes and demonstrate that this interaction is conserved in Salvador's mammalian homolog. Using native MS, we show that each of these complexes is dimeric in solution. We also measured the stability of each SARAH domain complex, finding that despite similarities at both the sequence and structural levels, SARAH domain complexes differ in stability. The identity, stoichiometry, and stability of these interactions characterized here comprehensively reveal the nature of SARAH domain–mediated complex formation and provide mechanistic insights into how SARAH domain–mediated interactions influence Hippo pathway activity.

Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7−/− mice. Although palmitoylation of barttin in kidneys of Zdhhc7−/− animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7−/− mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.

The Hong Kong Special Administrative Region Government today welcomed the promulgation of the Meteorological Development Plan for the Guangdong-Hong Kong-Macao Greater Bay Area (2020-2035) by the China Meteorological Administration.

In a statement, the Hong Kong SAR Government said the promulgation of the plan would further strengthen meteorological co-operation among Guangdong, Hong Kong and Macau in areas such as data sharing, scientific research and innovation, and training of meteorological personnel.

Such co-operation would in turn enhance the meteorological services in the three places, it added.

The relevant co-operation initiatives will benefit the Hong Kong Observatory (HKO) in its development of fine-scale meteorological monitoring, warning and forecasting services, and will further enhance Hong Kong's capability in forecasting extreme weather events, the statement said, adding the HKO will take forward the initiatives in collaboration with the relevant authorities in Guangdong and Macau.

The full text of the meteorological plan is available on the China Meteorological Administration's website. It can also be accessed via the Hong Kong SAR Government's Greater Bay Area and HKO websites.

Carlos Gustavo T. Moreira, Maria José Pacifico and Sergio Romaña Ibarra
Bull. Amer. Math. Soc. 57 (2018), 269-292.
Abstract, references and article information

(Impact Journals LLC) Volume 11, Issue 18 of @Oncotarget Clinical implications of chromatin accessibility assessed by ATAC-seq profiling in human cancers especially in a large patient cohort is largely unknown.

(Princeton University, Engineering School) New findings about critical cellular structures have upended common assumptions about their formation and composition and provided new insight how molecular machines are built in living cells.

The Hong Kong Special Administrative Region (HKSAR) Government welcomes the promulgation of the Meteorological Development Plan ...

(University of Córdoba) The University of Cordoba participated in the first shaping of a hydrological model on a basin scale as a global model to advance in world hydrological predictions.

(NIH/National Institute of Allergy and Infectious Diseases) A randomized, controlled clinical trial evaluating the safety and efficacy of a treatment regimen of the investigational antiviral remdesivir plus the anti-inflammatory drug baricitinib for COVID-19 has begun. The trial is now enrolling hospitalized adults with COVID-19 in the United States. The trial is expected to open at approximately 100 US and international sites. Investigators currently anticipate enrolling more than 1,000 participants. The National Institute of Allergy and Infectious Diseases is sponsoring the trial.

(Rice University) Rice University researchers have discovered a hidden symmetry in the chemical kinetic equations scientists have long used to model and study many of the chemical processes essential for life.

(Simon Fraser University) SFU professor Caroline Colijn’s research and data modelling to map the spread of COVID-19 in British Columbia has helped her procure funding from Genome B.C., a non-profit research organization that leads genomics innovation on Canada’s West Coast.

(Universitat Pompeu Fabra - Barcelona) Expansions by groups of humans were common during prehistoric times, after the adoption of agriculture. Among other factors, this is due to population growth of farmers which was greater than of that hunter-gatherers. We can find one example of this during the Neolithic period, when farming was introduced to Europe by migrations from the Middle East.

(Texas A&M University) Spoiling foods, souring wine and worsening wounds have a common culprit -- a process called oxidation. Although the ill effects of these chemical reactions can be curtailed by antioxidants, creating a sturdy platform capable of providing prolonged antioxidant activity is an ongoing challenge.

(Bentham Science Publishers) This comprehensive review presented by researchers from K.S. Rangasamy College of Arts and Science, Tiruchengode, Tamil-Nadu, India, gives readers a brief overview of phytoconstituents, nutritional values and medicinal properties of the plant.

(NOAA Headquarters) While the global average number of tropical cyclones each year has not budged from 86 over the last four decades, climate change has been influencing the locations of where these deadly storms occur, according to new NOAA-led research published in Proceedings of the National Academy of Science.

(George Mason University) Nathan Sleeter, Research Assistant Professor, Roy Rosenzweig Center for History and New Media (RRCHNM), is directing a project in which RRCHNM will create three classroom simulations based on events from the history of diplomacy for secondary education instructors.

(Purdue University) New environmentally friendly technologies promise to be 'game changers' in the rare earth metals field and enable the US to create a more stable and reliable domestic source of these essential metals. Purdue University patented extraction and purifying processes using ligand-assisted chromatography are shown to remove and purify such metals from coal ash, recycled magnets and raw ore safely, efficiently and with virtually no detrimental environmental impact.

(American Association for the Advancement of Science) While an effective vaccine for the SARS-CoV-2 virus is likely many months away, development could be accelerated by conducting controlled human infection (CHI) studies -- which are increasingly being considered by the scientific community due to the urgent need.