A re-evaluation of Cheilolejeunea subgenus Xenolejeunea

Cheilolejeunea subgenus Xenolejeunea Kachroo & Schust. is emended to account for variability observed in stem anatomy and lobule structure. Cheilolejeunea subgenus Tegulilejeunea Schust. is reduced to synonymy with subgenus Xenolejeunea. A new sectional classification of subgenus Xenolejeunea is proposed (sections Gigantae, Meyenianae, and Xenolejeunea). A key distinguishes among the sections and the 10 species accepted in the subgenus, which is known from Australasia, Oceania and tropical Asia. A nomenclator and discussion is provided for each species. Comments on excluded species conclude the treatment

An overview of the Lejeuneaceae in Australia

As currently understood, the Lejeuneaceae flora of Australia consists of 122 species in 27 genera. The family occurs almost exclusively in rainforested areas along the eastern coast of the continent. Based on species composition, three floristic regions are recognized: tropical, subtropical and temperate. The tropical region contains 80 percent of the total number of Lejeuneaceae found in Australia, the subtropical region contains 45 percent, and the temperate region only 15 percent of the total flora. The affinities of the Lejeuneaceae in the tropical and subtropical regions are strongest with the Asian flora, and those of the temperate region are strongest with the New Zealand flora. The diversity of the Lejeuneaceae flora in Australia is higher than might be expected for a non-equatorial region. This diversity may result from the wide variety of rainforest habitats that are available along both latitudinal and altitudinal gradients. The temperate flora is probably derived from that which existed in Australia, New Zealand, Antarctica and probably southern South America prior to the breakup of Gondwanaland. The modern tropical flora is probably a mixture of species that were part of the original northern Gondwanan flora and those that have invaded more recently

Quantum Error Correction for Quantum Memories

Active quantum error correction using qubit stabilizer codes has emerged as a promising, but experimentally challenging, engineering program for building a universal quantum computer. In this review we consider the formalism of qubit stabilizer and subsystem stabilizer codes and their possible use in protecting quantum information in a quantum memory. We review the theory of fault-tolerance and quantum error-correction, discuss examples of various codes and code constructions, the general quantum error correction conditions, the noise threshold, the special role played by Clifford gates and the route towards fault-tolerant universal quantum computation. The second part of the review is focused on providing an overview of quantum error correction using two-dimensional (topological) codes, in particular the surface code architecture. We discuss the complexity of decoding and the notion of passive or self-correcting quantum memories. The review does not focus on a particular technology but discusses topics that will be relevant for various quantum technologies.Comment: Final version: 47 pages, 17 Figs, 311 reference

Bell Inequalities and the Separability Criterion

We analyze and compare the mathematical formulations of the criterion for separability for bipartite density matrices and the Bell inequalities. We show that a violation of a Bell inequality can formally be expressed as a witness for entanglement. We also show how the criterion for separability and a description of the state by a local hidden variable theory, become equivalent when we restrict the set of local hidden variable theories to the domain of quantum mechanics. This analysis sheds light on the essential difference between the two criteria and may help us in understanding whether there exist entangled states for which the statistics of the outcomes of all possible local measurements can be described by a local hidden variable theory.Comment: 16 pages Revtex, typo in equation (14) correcte

Guidelines for the Provision of Garbage Reception Facilities at Ports Under MARPOL Annex V

This report offers guidelines for the provision of adequate port reception facilities for vessel-generated garbage under the requirements of Annex V of the International Convention for the Prevention of Pollution From Ships, 1973 (MARPOL 73/78), Regulations for the Prevention of Pollution by Garbage from Ships. MARPOL Annex V prohibits at-sea disposal of plastic materials from vessels, and specifies the distance from shore at which other materials may be dumped. Annex V also requires the provision of port reception facilities for garbage, but it does not specify these facilities or how they are to be provided. Since the at-sea dumping restrictions apply to all vessels, the reception facility requirement applies to all ports, terminals, and marinas that serve vessels. These guidelines were prepared to assist port owners and operators in meeting their obligation to provide adequate reception facilities for garbage. The report synthesizes available information and draws upon experience from the first years ofimplementation of MARPOL Annex V. (PDF file contains 55 pages.

Serve or Skip: The Power of Rejection in Online Bottleneck Matching

We consider the online matching problem, where n server-vertices lie in a metric space and n request-vertices that arrive over time each must immediately be permanently assigned to a server-vertex.We focus on the egalitarian bottleneck objective, where the goal is to minimize the maximum distance between any request and its server. It has been demonstrated that while there are effective algorithms for the utilitarian objective (minimizing total cost) in the resource augmentation setting where the offline adversary has half the resources, these are not effective for the egalitarian objective. Thus, we propose a new Serve-or-Skip bicriteria analysis model, where the online algorithm may reject or skip up to a specified number of requests, and propose two greedy algorithms: GRI NN(t) and GRIN(t) . We show that the Serve-or-Skip model of resource augmentation analysis can essentially simulate the doubled-server capacity model, and then examine the performance of GRI NN(t) and GRIN(t)

The Bounded Storage Model in The Presence of a Quantum Adversary

An extractor is a function E that is used to extract randomness. Given an imperfect random source X and a uniform seed Y, the output E(X,Y) is close to uniform. We study properties of such functions in the presence of prior quantum information about X, with a particular focus on cryptographic applications. We prove that certain extractors are suitable for key expansion in the bounded storage model where the adversary has a limited amount of quantum memory. For extractors with one-bit output we show that the extracted bit is essentially equally secure as in the case where the adversary has classical resources. We prove the security of certain constructions that output multiple bits in the bounded storage model.Comment: 13 pages Latex, v3: discussion of independent randomizers adde