Weightlessness simulation system and process

A weightlessness simulator has a chamber and a suit in the chamber. O-rings and valves hermetically seal the chamber. A vacuum pump connected to the chamber establishes a pressure in the chamber less than atmospheric pressure. A water supply tank and water supply line supply a body of water to the chamber as a result of partial vacuum created in the chamber. In use, an astronaut enters the pressure suit through a port, which remains open to ambient atmosphere, thus supplying air to the astronaut during use. The pressure less than atmospheric pressure in the chamber is chosen so that the pressure differential from the inside to the outside of the suit corresponds to the pressure differential with the suit in outer space

Quantum Encodings in Spin Systems and Harmonic Oscillators

We show that higher-dimensional versions of qubits, or qudits, can be encoded into spin systems and into harmonic oscillators, yielding important advantages for quantum computation. Whereas qubit-based quantum computation is adequate for analyses of quantum vs classical computation, in practice qubits are often realized in higher-dimensional systems by truncating all but two levels, thereby reducing the size of the precious Hilbert space. We develop natural qudit gates for universal quantum computation, and exploit the entire accessible Hilbert space. Mathematically, we give representations of the generalized Pauli group for qudits in coupled spin systems and harmonic oscillators, and include analyses of the qubit and the infinite-dimensional limits.Comment: 4 pages, published versio

Effects of crucible wetting during solidification of immiscible Pb-Zn

Many industrial uses for liquid phase miscibility gap alloys are proposed. However, the commercial production of these alloys into useful ingots with a reasonable amount of homogeneity is arduous because of their immiscibility in the liquid state. In the low-g environment of space gravitational settling forces are abated, thus solidification of an immiscible alloys with a uniform distribution of phases becomes feasible. Elimination of gravitational settling and coalescence processes in low-g also makes possible the study of other separation and coarsening mechanisms. Even with gravitational separation forces reduced, many low-g experiments have resulted in severely segregated structures. The segregation in many cases was due to preferential wetting of the crucible by one of the immiscible liquids. The objective was to analyze the wetting behavior of Pb-Zn alloys on various crucible materials in an effort to identify a crucible in which the fluid flow induced by preferential wetting is minimized. It is proposed that by choosing the crucible for a particular alloy so that the difference in surface energy between the solid and two liqud phases is minimized, the effects of preferential wetting can be diminished and possibly avoided. Qualitative experiments were conducted and have shown the competitive wetting behavior of the immiscible Pb-Zn system and 13 different crucible materials

Rational invariants of even ternary forms under the orthogonal group

In this article we determine a generating set of rational invariants of minimal cardinality for the action of the orthogonal group $\mathrm{O}_3$ on the space $\mathbb{R}[x,y,z]_{2d}$ of ternary forms of even degree $2d$. The construction relies on two key ingredients: On one hand, the Slice Lemma allows us to reduce the problem to dermining the invariants for the action on a subspace of the finite subgroup $\mathrm{B}_3$ of signed permutations. On the other hand, our construction relies in a fundamental way on specific bases of harmonic polynomials. These bases provide maps with prescribed $\mathrm{B}_3$-equivariance properties. Our explicit construction of these bases should be relevant well beyond the scope of this paper. The expression of the $\mathrm{B}_3$-invariants can then be given in a compact form as the composition of two equivariant maps. Instead of providing (cumbersome) explicit expressions for the $\mathrm{O}_3$-invariants, we provide efficient algorithms for their evaluation and rewriting. We also use the constructed $\mathrm{B}_3$-invariants to determine the $\mathrm{O}_3$-orbit locus and provide an algorithm for the inverse problem of finding an element in $\mathbb{R}[x,y,z]_{2d}$ with prescribed values for its invariants. These are the computational issues relevant in brain imaging.Comment: v3 Changes: Reworked presentation of Neuroimaging application, refinement of Definition 3.1. To appear in "Foundations of Computational Mathematics

State-independent preparation uncertainty relations

The standard state-dependent Heisenberg-Robertson uncertainly-relation lower bound fails to capture the quintessential incompatibility of observables as the bound can be zero for some states. To remedy this problem, we establish a class of tight (i.e., inequalities are saturated)variance-based sum-uncertainty relations derived from the Lie algebraic properties of observables and show that our lower bounds depend only on the irreducible representation assumed carried by the Hilbert space of state of the system. We illustrate our result for the cases of the Weyl-Heisenberg algebra, special unitary algebras up to rank 4, and any semisimple compact algebra. We also prove the usefulness of our results by extending a known variance-based entanglement detection criterion.Comment: 7 pages, 1 figur

Characterising the role of Vibrio vulnificus type 6 secretion systems 1 and 2 in an in vivo oyster model

Vibrio vulnificus is a significant human pathogen commonly isolated from temperate marine environments, where it is particularly abundant within filter-feeding shellfish. V. vulnificus is currently increasing in prevalence, theorised to be due to climate change facilitating V. vulnificus growth in previously inhospitable environments. Infection of susceptible individuals with V. vulnificus typically results in either primary septicaemia or necrotic wound infection, depending upon the route of entry, and frequently results in death if not treated rapidly. Two type 6 secretion systems (T6SS) have been identified in V. vulnificus, termed the T6SS1 and the T6SS2. The T6SS is a molecular syringe utilised to inject cytotoxic effector proteins into neighbouring cells. Whilst the T6SS2 is present in all sequenced V. vulnificus strains, only a subset possesses the T6SS1. Previous bacterial co-culture killing assays between T6SS1+ and T6SS1- V. vulnificus strains demonstrated thermoregulated T6SS1-mediated killing of T6SS1- strains. This study further characterised the role of both the T6SS1 and the T6SS2 in vitro. In vitro co-culture assays demonstrated that both the T6SS1 and the T6SS2 have antibacterial killing activity at the environmentally representative temperature of 21 °C. This is the first characterised role for the T6SS2 of V. vulnificus. No anti-eukaryotic activity was observed following co-culture with the phagocytic amoeba, Dictyostelium discoideum, suggesting that T6SS activity is purely antibacterial. In vitro bacterial co-culture assays were replicated in vivo using an oyster model. To facilitate high-level uptake of bacterial strains of interest by oysters, an artificial marine snow model was developed where bacteria were incorporated into easily ingested phytoplankton aggregates. Uptake of bacteria from artificial marine snow was extremely successful, resulting in bacterial loads within oysters significantly greater than achieved by any study to date. Using this model, this study was able to demonstrate that V. vulnificus utilises both the T6SS1 and the T6SS2 to target and kill neighbouring bacteria, in both an intra and inter-species manner. This data suggests that the T6SSs of V. vulnificus play a key role in V. vulnificus ecology and the dynamics between bacterial populations in vivo