Volume distortion in groups

Given a space $Y$ in $X$, a cycle in $Y$ may be filled with a chain in two ways: either by restricting the chain to $Y$ or by allowing it to be anywhere in $X$. When the pair $(G,H)$ acts on $(X, Y)$, we define the $k$-volume distortion function of $H$ in $G$ to measure the large-scale difference between the volumes of such fillings. We show that these functions are quasi-isometry invariants, and thus independent of the choice of spaces, and provide several bounds in terms of other group properties, such as Dehn functions. We also compute the volume distortion in a number of examples, including characterizing the $k$-volume distortion of $\Z^k$ in $\Z^k \rtimes_M \Z$, where $M$ is a diagonalizable matrix. We use this to prove a conjecture of Gersten.Comment: 27 pages, 10 figure

Irrversibility of Entanglement Manipulations: Vagueness of the Entanglement of Cost and Entanglement of Distillation

We show that the entanglement of cost and entanglement of distillation can be vague when we consider a more general form of entanglement manipulation in which we collectively deal with not only states of our concern but also other states. We introduce the most general entanglement manipulation in which the formation and distillation can be simultaneously performed. We show that in a certain case entanglement manipulations are reversible with respect to the most general entanglement manipulation. This broadens our scope of vision on the irreversibility of entanglement manipulations.Comment: Typos and minor errors corrected, 3 pages, RevTe

Subsurface microstructural changes in a cast heat resisting alloy caused by high temperature corrosion

A cast HP ModNb alloy (Fe–25Cr–35Ni–1Nb, wt.%) was oxidised and carburised in CO–CO2 corresponding to aC = 0.1 and pO2 = 3 1016 atm at 1080 C. Formation of an external, chromium-rich oxide scale led to depletion of this metal in a deep alloy subsurface zone. Within that zone, secondary chromium-rich carbides dissolved, primary carbides oxidised, solute silicon and aluminium internally oxidised, and extensive porosity developed. Pore volumes correspond to the difference between metal loss by scaling and metal displacement by internal oxidation, assuming the scale–metal interface to be fixed. The pores are concluded to be Kirkendall void

Quantum Cryptography without Public Announcement of Bases

This paper provides a simple variation of the basic ideas of the BB84 quantum cryptographic scheme leading to a method of key expansion. A secure random sequence (the bases sequence) determines the encoding bases in a proposed scheme. Using the bases sequence repeatedly is proven to be safe by quantum mechanical laws.Comment: 4 page

Entanglement Measures with Asymptotic Weak-Monotonicity as Lower (Upper) Bound for the Entanglement of Cost (Distillation)

We propose entanglement measures with asymptotic weak-monotonicity. We show that a normalized form of entanglement measures with the asymptotic weak-monotonicity are lower (upper) bound for the entanglement of cost (distillation).Comment: 3 pages, RevTe

Gravitational Lensing of Relativistic Fireball

The gravitational lensing of a relativistic fireball can produce the time delayed multiple images with quite different spectra and temporal patterns in contrast with a nonrelativistic source and hence can imitate the source recurrence. In particular, the enigmatic four multiple gamma-ray bursts detected during two days at October 1996 in the same sky region may be due to a single fireball event multiply imaged by the foreground galactic nucleus or cluster of galaxies.Comment: 8 pages, 1 figure; accepted for publication in Phys.Lett.

Eavesdropper's Optimal Information in Variations of Bennett-Brassard 1984 Quantum Key Distribution in the Coherent Attacks

We calculate eavesdropper's optimal information on raw bits in Bennett-Brassard 1984 quantum key distribution (BB84 QKD) and six-state scheme in coherent attacks, using a formula by Lo and Chau [Science 283 (1999) 2050] with single photon assumption. We find that eavesdropper's optimal information in QKD without public announcement of bases [Phys. Lett. A 244 (1998) 489] is the same as that of a corresponding QKD WITH it in the coherent attack. We observe a sum-rule concerning each party's information.Comment: no correction, 7 pages, 1 figure, RevTe

Evaluation of the National Compact – Aspirations and Impact

Compacts are written agreements that articulate the vision for cooperation between governments and the not-for-profit sector, generally with the overall aim of improving social outcomes. This report documents an evaluation which assessed the implementation and impact of Australia’s National Compact, and the extent to which it has contributed to improved relationships between Federal government agencies and the not-for-profit sector. Findings from interviews, focus groups and surveys captured the perspectives of leaders in the not-for-profit sector and staff in government agencies about the relationship between the sectors, and the role the Compact has played in improving this relationship. Government and not-for-profit stakeholders strongly value the sector relationship and perceive it to be improving, with two thirds of the respondents in the government survey and almost fifty percent in the not-for-profit survey characterising the relationship as strong. The Compact has formalised the importance of the relationship, raised expectations within government agencies and the not-for-profit sector and provided an important symbol and foundation for mutual commitment to improving the relationship. However, awareness of the Compact remains inconsistent; there is limited understanding of the way the Compact has underpinned important elements of not-for-profit reform; and many perceive Compact implementation has lost momentum. As a result, there is limited attribution of improvements in the sector relationship to the Compact. Australia has a critical need for a constructive government-not-for-profit partnership working towards more effective and efficient delivery of social outcomes. In the context of its ageing population and socio-demographic challenges, there will be significantly increasing pressure to deliver stronger outcomes with fewer resources. In this context, the Compact has a vital role to play. The evidence in this report suggests that to build on the Compact’s solid foundation and ensure long term impact, a renewed commitment is needed from leaders of the not-for-profit sector as well as bipartisan support from government. Action is needed to continue to build awareness of the Compact, its aims, actions and outcomes, and its achievements in articulating the foundations for not-for-profit reform. A clearer logic framework linking Compact aspirations to actions and outcomes is needed, to inform continued implementation across both sectors. Establishment of a monitoring framework and an annual Relationship Scorecard would drive on-going refinement of the implementation as well as increased awareness of and commitment to the Compact and its intended outcomes

Fundamental Symmetries and Conservation Laws

I discuss recent progress in low-energy tests of symmetries and conservation laws, including parity nonconservation in atoms and nuclei, electric dipole moment tests of time-reversal invariance, beta-decay correlation studies, and decays violating separate (family) and total lepton number.Comment: 11 pages, 5 figures; plenary talk presented at PANIC0

Evolution of entanglement within classical light states

We investigate the evolution of quantum correlations over the lifetime of a multi-photon state. Measurements reveal time-dependent oscillations of the entanglement fidelity for photon pairs created by a single semiconductor quantum dot. The oscillations are attributed to the phase acquired in the intermediate, non-degenerate, exciton-photon state and are consistent with simulations. We conclude that emission of photon pairs by a typical quantum dot with finite polarisation splitting is in fact entangled in a time-evolving state, and not classically correlated as previously regarded