The new mineral tombstoneite (IMA2021-053), (Ca0.5Pb0.5)Pb3Cu2+6Te6+2O6(Te4+O3)6(Se4+O3)2(SO4)2⋅3H2O, occurs at the Grand Central mine in the Tombstone district, Cochise County, Arizona, USA, in cavities in quartz matrix in association with jarosite and rodalquilarite. Tombstoneite crystals are green pseudohexagonal tablets, up to 100 μm across and 20 μm thick. The mineral has a pale green streak and adamantine lustre. It is brittle with irregular fracture and a Mohs hardness of ~2½. It has one perfect cleavage on {001}. The calculated density is 5.680 g cm–3. Optically, the mineral is uniaxial (–) and exhibits pleochroism: O = green, E = light yellow green; O > E. The Raman spectrum exhibits bands consistent with Te6+O6, Te4+O3, Se4+O3 and SO4. Electron microprobe analysis provided the empirical formula (Ca0.51Pb0.49)Σ1.00Pb3.00Cu2+5.85Te6+2.00O6(Te4+1.00O3)6(Se4+0.69Te4+0.24S0.07O3)2(S1.00O4)2⋅3H2O. Tombstoneite is trigonal, P321, a = 9.1377(9), c = 12.2797(9) Å, V = 887.96(18) Å3 and Z = 1. The structure of tombstoneite (R1 = 0.0432 for 1205 I > 2σI) contains thick heteropolyhedral layers comprising Te6+O6 octahedra, Jahn-Teller distorted Cu2+O5 pyramids, Te4+O3 pyramids and Se4+O3 pyramids. Pb2+ cations without stereoactive 6s2 lone-pair electrons are hosted in pockets in the heteropolyhedral layer. Pb2+ cations, possibly with stereoactive 6s2 lone-pair electrons, are located in the interlayer region along with SO4 tetrahedra and H2O groups. Within the heteropolyhedral layer, the Te6+O6 octahedra and the Te4+O3 pyramids form finite Te6+O3(Te4+O3)3 clusters with a pinwheel-like configuration. This is the first known finite complex including both Te4+ and Te6+ polyhedra in any natural or synthetic tellurium oxysalt structure.

We consider the use of sparsity-promoting norms in obtaining localised forcing structures from resolvent analysis. By formulating the optimal forcing problem as a Riemannian optimisation, we are able to maximise cost functionals whilst maintaining a unit-energy forcing. Taking the cost functional to be the energy norm of the driven response results in a traditional resolvent analysis and is solvable by a singular value decomposition (SVD). By modifying this cost functional with the $L_1$-norm, we target spatially localised structures that provide an efficient amplification in the energy of the response. We showcase this optimisation procedure on two flows: plane Poiseuille flow at Reynolds number $Re=4000$, and turbulent flow past a NACA 0012 aerofoil at $Re=23\,000$. In both cases, the optimisation yields sparse forcing modes that maintain important features of the structures arising from an SVD in order to provide a gain in energy. These results showcase the benefits of utilising a sparsity-promoting resolvent formulation to uncover sparse forcings, specifically with a view to using them as actuation locations for flow control.

The new mineral flaggite (IMA2021-044), Pb4Cu2+4Te6+2(SO4)2O11(OH)2(H2O), occurs at the Grand Central mine in the Tombstone district, Cochise County, Arizona, USA, in cavities in quartz matrix in association with alunite, backite, cerussite, jarosite and rodalquilarite. Flaggite crystals are lime-green to yellow-green tablets, up to 0.5 mm across. The mineral has a very pale green streak and adamantine lustre. It is brittle with irregular fracture and a Mohs hardness of ~3. It has one excellent cleavage on {010}. The calculated density is 6.137 g cm–3. Optically, the mineral is biaxial (+) with α = 1.95(1), β = 1.96(1), γ = 2.00(1) (white light); 2V = 54(2)°; pleochroism: X green, Y light yellow green, Z nearly colourless; X > Y > Z. The Raman spectrum exhibits bands consistent with TeO6 and SO4. Electron microprobe analysis provided the empirical formula Pb3.88Cu2+3.89Te6+2.08(SO4)2O11(OH)2(H2O) (–0.03 H). Flaggite is triclinic, P1, a = 9.5610(2), b = 9.9755(2), c = 10.4449(3) Å, α = 74.884(1), β = 89.994(1), γ = 78.219(1)°, V = 939.97(4) Å3 and Z = 2. The structure of flaggite (R1 = 0.0342 for 5936 I > 2σI) contains hexagonal-close-packed, stair-step-like layers comprising TeO6 octahedra and Jahn-Teller distorted CuO6 octahedra. The layers in the structure of flaggite are very similar to those in bairdite, timroseite and paratimroseite.

Dendoraite-(NH4), (NH4)2NaAl(C2O4)(PO3OH)2(H2O)2, is a new mineral species from the Rowley mine, Maricopa County, Arizona, USA. It occurs in an unusual bat-guano-related, post-mining assemblage of phases that include a variety of vanadates, phosphates, oxalates and chlorides, some containing NH4+. Other secondary minerals found in association with dendoraite-(NH4) are antipinite, fluorite, mimetite, mottramite, relianceite-(K), rowleyite, salammoniac, struvite, vanadinite, willemite, wulfenite and at least one other new mineral. Crystals of dendoraite-(NH4) are colourless blades up to ~0.1 mm in length. The streak is white and lustre is vitreous, Mohs hardness is 2½, tenacity is brittle and fracture is splintery. The calculated density is 2.122 g⋅cm–3. Dendoraite-(NH4) is optically biaxial (–) with α = 1.490(5), β = 1.540(5) and γ = 1.541(5) (white light); 2Vcalc = 15.7°; and orientation X = b. Electron microprobe analysis gave the empirical formula [(NH4)1.48K0.52]Σ2.00Na0.96(Al0.96Fe3+0.03)Σ0.99(C2O4)[PO2.97(OH)1.03]2(H2O)2, with the C, N and H contents constrained by the crystal structure. Dendoraite-(NH4) is monoclinic, P21/n, with a = 10.695(6), b = 6.285(4), c = 19.227(12) Å, β = 90.933(10)°, V = 1292(2) Å3, and Z = 4. The structural unit in the crystal structure of dendoraite-(NH4) (R1 = 0.0467 for 1322 Io > 2σI reflections) is a double-strand chain of corner-sharing AlO6 octahedra and PO3OH tetrahedra decorated by additional PO3OH tetrahedra and C2O4 groups. Topologically, this is the same chain found in the structure of thebaite-(NH4). The decorated chains connect to one another through links to NaO7(H2O) polyhedra to form a [Na(H2O)Al(C2O4)(PO3OH)2]2– sheet, which connect to one another through bonds to (NH4)/K and through hydrogen bonds.

Relianceite-(K), K4Mg(V4+O)2(C2O4)(PO3OH)4(H2O)10, is a new mineral species from the Rowley mine, Maricopa County, Arizona, USA. It occurs in an unusual bat-guano-related, post-mining assemblage of phases. Other secondary minerals associated with relianceite-(K) are antipinite, dendoraite-(NH4), fluorite, mimetite, mottramite, rowleyite, salammoniac, struvite, vanadinite, willemite, wulfenite and at least one other new mineral. Crystals of relianceite-(K) are sky blue prisms up to ~0.1 mm in length. The streak is very pale blue and lustre is vitreous, Mohs hardness is 2½, tenacity is brittle and fracture is splintery. The calculated density is 2.111 g⋅cm–3. Relianceite-(K) is optically biaxial (+) with α = 1.528(2), β = 1.529(2), γ = 1.562(2) (white light); 2Vmeas = 22(1)°; orientation Z = b; pleochroism: X = colourless, Y = pale blue, Z = pale blue; X < Y ≈ Z. Electron microprobe analysis gave the empirical formula [K2.21(NH4)1.79]Σ4.00Mg0.96(V4+0.95O)2(C2O4)[P1.03O3.03(OH)0.97]4(H2O)10, with the C, N and H contents constrained by the crystal structure. Raman spectroscopy confirmed the presence of NH4 and C2O4. Relianceite-(K) is monoclinic, Pc, with a = 12.404 (7) Å, b = 9.014 (6), c = 13.260 (8) Å, β = 100.803(10)°, V = 1456 (2) Å3 and Z = 2. The structural unit in the crystal structure of relianceite-(K) (R1 = 0.0540 for 3751 Io > 2σI reflections) is a (V4+O)2(C2O4)(PO3OH)4 chain in which VO6 octahedra are bridged by an oxalate group to form [V2C2O12] dimers, PO3OH tetrahedra form a double bridge between the VO6 octahedra of the dimers, and additional PO3OH tetrahedra decorate the chain. Topologically, this is the same chain found in the structure of davidbrownite-(NH4). The MgO(H2O)5 octahedron can be considered a distant decoration on the chain. The chains are linked to each other through an extensive system of K/NH4–O bonds and hydrogen bonds.

Native tungsten (IMA2011-004), W, is officially described as a new mineral from gold placers in the Bol'shaya Pol'ya river valley, Prepolar Urals, Russia, associated with yttriaite-(Y) and from quartz veins in the Mt Neroyka rock-crystal field, Ust–Puiva, Tyumenskaya Oblast', Russia. Tungsten forms polycrystalline grains and masses, and rarely cubo-octahedra. It is silver white to steel grey in colour, with metallic lustre and grey streak. The calculated density is 19.226 g/cm3. The Vickers hardness (VHN25) is 571.45 kg/mm2. In plane polarised light, tungsten is white with a pale-yellow tint and optically isotropic. Electron microprobe analyses of Bol'shaya Pol'ya river valley material provided W 99.27, Mo 0.06, Mn 0.04, Fe 0.01, total 99.38 wt.%. The five strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 2.2422(100)(110), 1.5835(25)(200), 1.2929(48)(211), 1.0010(23)(310) and 0.8457(24)(321). Tungsten is cubic, Im$\bar{3}$m, a = 3.1648(4) Å, V = 31.69(4) Å3 and Z = 2. Some additional occurrences of native tungsten and technogenic tungsten found in Nature are also described.

This SHEA white paper identifies knowledge gaps and challenges in healthcare epidemiology research related to coronavirus disease 2019 (COVID-19) with a focus on core principles of healthcare epidemiology. These gaps, revealed during the worst phases of the COVID-19 pandemic, are described in 10 sections: epidemiology, outbreak investigation, surveillance, isolation precaution practices, personal protective equipment (PPE), environmental contamination and disinfection, drug and supply shortages, antimicrobial stewardship, healthcare personnel (HCP) occupational safety, and return to work policies. Each section highlights three critical healthcare epidemiology research questions with detailed description provided in supplementary materials. This research agenda calls for translational studies from laboratory-based basic science research to well-designed, large-scale studies and health outcomes research. Research gaps and challenges related to nursing homes and social disparities are included. Collaborations across various disciplines, expertise and across diverse geographic locations will be critical.

Single-particle reconstruction can be used to perform three-dimensional (3D) imaging of homogeneous populations of nano-sized objects, in particular viruses and proteins. Here, it is demonstrated that it can also be used to obtain 3D reconstructions of heterogeneous populations of inorganic nanoparticles. An automated acquisition scheme in a scanning transmission electron microscope is used to collect images of thousands of nanoparticles. Particle images are subsequently semi-automatically clustered in terms of their properties and separate 3D reconstructions are performed from selected particle image clusters. The result is a 3D dataset that is representative of the full population. The study demonstrates a methodology that allows 3D imaging and analysis of inorganic nanoparticles in a fully automated manner that is truly representative of large particle populations.

Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.

Since the beginning of 2020, the coronavirus disease (COVID-19) pandemic has dramatically influenced almost every aspect of human life. Activities requiring human gatherings have either been postponed, canceled, or held completely virtually. To supplement lack of in-person contact, people have increasingly turned to virtual settings online, advantages of which include increased inclusivity and accessibility and a reduced carbon footprint. However, emerging online technologies cannot fully replace in-person scientific events. In-person meetings are not susceptible to poor Internet connectivity problems, and they provide novel opportunities for socialization, creating new collaborations and sharing ideas. To continue such activities, a hybrid model for scientific events could be a solution offering both in-person and virtual components. While participants can freely choose the mode of their participation, virtual meetings would most benefit those who cannot attend in-person due to the limitations. In-person portions of meetings should be organized with full consideration of prevention and safety strategies, including risk assessment and mitigation, venue and environmental sanitation, participant protection and disease prevention, and promoting the hybrid model. This new way of interaction between scholars can be considered as a part of a resilience system, which was neglected previously and should become a part of routine practice in the scientific community.

To understand hospital policies and practices as the COVID-19 pandemic accelerated, the Society for Healthcare Epidemiology of America (SHEA) conducted a survey through the SHEA Research Network (SRN). The survey assessed policies and practices around the optimization of personal protection equipment (PPE), testing, healthcare personnel policies, visitors of COVID-19 patients in relation to procedures, and types of patients. Overall, 69 individual healthcare facilities responded in the United States and internationally, for a 73% response rate.

The extent of intertidal flats in the Yellow Sea region has declined significantly in the past few decades, resulting in severe population declines in several waterbird species. The Yellow Sea region holds the primary stopover sites for many shorebirds during their migration to and from northern breeding grounds. However, the functional roles of these sites in shorebirds’ stopover ecology remain poorly understood. Through field surveys between July and November 2015, we investigated the stopover and moult schedules of migratory shorebirds along the southern Jiangsu coast, eastern China during their southbound migration, with a focus on the ‘Critically Endangered’ Spoon-billed Sandpiper Calidris pygmaea and ‘Endangered’ Nordmann’s Greenshank Tringa guttifer. Long-term count data indicate that both species regularly occur in globally important number in southern Jiangsu coast, constituting 16.67–49.34% and 64.0–80.67% of their global population estimates respectively, and it is highly likely that most adults undergo their primary moult during this southbound migration stopover. Our results show that Spoon-billed Sandpiper and Nordmann’s Greenshank staged for an extended period of time (66 and 84 days, respectively) to complete their primary moult. On average, Spoon-billed Sandpipers and Nordmann’s Greenshanks started moulting primary feathers on 8 August ± 4.52 and 27 July ± 1.56 days respectively, and their moult durations were 72.58 ± 9.08 and 65.09 ± 2.40 days. In addition, some individuals of several other shorebird species including the ‘Endangered’ Great Knot Calidris tenuirostris, ‘Near Threatened’ Bar-tailed Godwit Limosa lapponica, ‘Near Threatened’ Eurasian Curlew Numenius arquata and Greater Sand Plover Charadrius leschenaultii also underwent primary moult. Our work highlights the importance of the southern Jiangsu region as the primary moulting ground for these species, reinforcing that conservation of shorebird habitat including both intertidal flats and supratidal roosting sites in this region is critical to safeguard the future of some highly threatened shorebird species.