We provide an assessment of the Infinity Two Fusion Pilot Plant (FPP) baseline plasma physics design. Infinity Two is a four-field period, aspect ratio A = 10, quasi-isodynamic stellarator with improved confinement appealing to a max-J approach, elevated plasma density and high magnetic fields (⟨B⟩ = 9 T). At the envisioned operating point [800 MW deuterium-tritium (DT) fusion], the configuration has robust magnetic surfaces based on magnetohydrodynamic (MHD) equilibrium calculations and is stable to both local and global MHD instabilities. The configuration has excellent confinement properties with small neoclassical transport and low bootstrap current (|Ibootstrap| ∼ 2 kA). Calculations of collisional alpha particle confinement in a DT FPP scenario show small energy losses to the first wall (< 1.5%) and stable energetic particle/Alfvén eigenmodes at high ion density. Low turbulent transport is produced using a combination of density profile control consistent with pellet fueling and reduced stiffness to turbulent transport via three-dimensional shaping. Transport simulations with the T3D-GX-SFINCS code suite with self-consistent turbulent and neoclassical transport predict that the Pfus = 800 MW operating point is attainable with high fusion gain (Q = 40) at volume-averaged electron densities ne ≈ 2×1020 m−3, below the Sudo density limit. Additional transport calculations show that an ignited (Q = ∞) solution is available at slightly higher density (2.2×1020 m−3) with Pfus = 1.5 GW. The magnetic configuration is defined by a magnetic coil set with sufficient room for an island divertor, shielding and blanket solutions with tritium breeding ratios (TBR) above unity. An optimistic estimate for the gas-cooled solid breeder designed Helium Cooled Pebble Bed is TBR ∼ 1.3. Infinity Two satisfies the physics requirements of a stellarator fusion pilot plant.

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.

The SPARC tokamak is a critical next step towards commercial fusion energy. SPARC is designed as a high-field ($B_0 = 12.2$ T), compact ($R_0 = 1.85$ m, $a = 0.57$ m), superconducting, D-T tokamak with the goal of producing fusion gain $Q>2$ from a magnetically confined fusion plasma for the first time. Currently under design, SPARC will continue the high-field path of the Alcator series of tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in a compact device. The goal of $Q>2$ is achievable with conservative physics assumptions ($H_{98,y2} = 0.7$) and, with the nominal assumption of $H_{98,y2} = 1$, SPARC is projected to attain $Q \approx 11$ and $P_{\textrm {fusion}} \approx 140$ MW. SPARC will therefore constitute a unique platform for burning plasma physics research with high density ($\langle n_{e} \rangle \approx 3 \times 10^{20}\ \textrm {m}^{-3}$), high temperature ($\langle T_e \rangle \approx 7$ keV) and high power density ($P_{\textrm {fusion}}/V_{\textrm {plasma}} \approx 7\ \textrm {MW}\,\textrm {m}^{-3}$) relevant to fusion power plants. SPARC's place in the path to commercial fusion energy, its parameters and the current status of SPARC design work are presented. This work also describes the basis for global performance projections and summarizes some of the physics analysis that is presented in greater detail in the companion articles of this collection.

We study the dynamics of cash-and-carry arbitrage using the U.S. crude oil market. Sizable arbitrage-related inventory movements occur at the New York Mercantile Exchange (NYMEX) futures contract delivery point but not at other storage locations, where instead, operational factors explain most inventory changes. We add to the theory-of-storage literature by introducing two new features. First, due to arbitrageurs contracting ahead, inventories respond to not only contemporaneous but also lagged futures spreads. Second, storage-capacity limits can impede cash-and-carry arbitrage, leading to the persistence of unexploited arbitrage opportunities. Our findings suggest that arbitrage-induced inventory movements are, on average, price stabilizing.

The electrical characteristics of Au/Ni/Ti/ n-SiC contacts have been examined as a function of implant dose (1013-1014 ions/cm2) at 5 KeV and temperature of annealing (750-1000 °C). Measurements of specific contact resistance, ρc, were approximately constant at lower implant doses until increasing at 1 x 1015 ions/cm2 for both C and P ions. Annealing at a temperature of 1000 °C has reduced the value of ρc by an order of magnitude to ∼1 x 10-6 Ω.cm2 at implant doses of 1013-1014 ions/cm2. Auger Electron Spectroscopy (AES) has shown that annealing at 1000 °C resulted in a strong indiffusion of the metallization layers at the interface.

A cross-sectional study was conducted to investigate risk factors for sporadic Cryptosporidium infection in a paediatric population in Nigeria. Of 692 children, 134 (19·4%) were infected with Cryptosporidium oocysts. Cryptosporidium spp. were identified in 49 positive samples using PCR–restriction fragment length polymorphism and direct sequencing of the glycoprotein60 (GP60) gene. Generalized linear mixed-effects models were used to identify risk factors for all Cryptosporidium infections, as well as for C. hominis and C. parvum both together and separately. Risk factors identified for all Cryptosporidium infections included malaria infection and a lack of Ascaris infection. For C. hominis infections, stunting and younger age were highlighted as risk factors, while stunting and malaria infection were identified as risk factors for C. parvum infection.

The Vestimentifera, or deep-sea tube worms, comprise an ecologically and anatomically unusual group of marine invertebrates, with poorly understood biogeography, ecology, phylogenetic affinities and evolutionary radiation. To gain insight into evolutionary diversification within the group, we have used a molecular biological approach. We report the cloning of a region of 28S ribosomal DNA from representatives of five vestimentiferan genera plus, for comparison, a polychaete and a perviate pogonophore. Phylogenetic analyses using these DNA sequences confirm that Ridgeia and Tevnia are closely related genera. The analyses also lead us to propose the hypothesis that the earliest vestimentiferan lineage to diverge gave rise to the genus Lamellibrachia only. In addition, our comparative DNA sequence data now provide a means to use molecular methods for identification of deep-sea tube worms; we employed this approach to demonstrate that the first vestimentiferan specimen from the eastern Atlantic Ocean belongs to the genus Lamellibrachia. DNA-based identification should have wide applications in the study of vestimentiferan biogeography and ecology.

Use of the nautiloid cephalopod generic names Orthoceras and Michelinoceras is briefly reviewed. Two new genera, Imbricatoceras (upper Ordovician-Silurian) and Radnoroceras (Wenlock-Ludlow), are proposed for common taxa with distinctive ornamentation.

The revised classification of the Ludlovian rocks is defended. It is maintained that there is no need for separate rock-stratigraphical and biostratigraphical classifications. The nine new divisions are, therefore, combined units; their number is justified by the detailed mapping and their names are dictated by the requirements of the rocks and not by an arbitrary code of rules. The old classification, using Aymestry Limestone, is considered to be still usable as a crude rock-stratigraphical classification.

Convolute bedding is described from the Lower Ludlovian in north-eastern Radnorshire in calcareous siltstones probably of the Monograptus tumescenszone. Examples of true slump-structures from the same area are given for comparison. The mode of formation of the convolute bedding is discussed and reference made to such directional information as is available from a study of the sediments.

Previous views on the relationship between the thick continental deposits of the Dingle Group and the older fossiliferous Silurian rocks of the Dunquin Group are briefly reviewed. Detailed field evidence is presented showing that in the coastal sections of Coosgorrib, Coosglass, and Coosshaun there is faulting between the two groups. The same situation obtains at the northern end of the Great Blasket island. Fortunately inland exposures are sufficient to show that there is stratigraphical continuity from the lower Ludfordian (Ludlow) beds of the Croaghmarhin Formation, at the top of the Dunquin Group, into the purple siltstones of the Dingle Group. The Dingle Group is followed uncomformably by Upper Old Red Sandstone (essentially Upper Devonian).