26,613 research outputs found
Multi-party Quantum Computation
We investigate definitions of and protocols for multi-party quantum computing
in the scenario where the secret data are quantum systems. We work in the
quantum information-theoretic model, where no assumptions are made on the
computational power of the adversary. For the slightly weaker task of
verifiable quantum secret sharing, we give a protocol which tolerates any t <
n/4 cheating parties (out of n). This is shown to be optimal. We use this new
tool to establish that any multi-party quantum computation can be securely
performed as long as the number of dishonest players is less than n/6.Comment: Masters Thesis. Based on Joint work with Claude Crepeau and Daniel
Gottesman. Full version is in preparatio
Small Pseudo-Random Families of Matrices: Derandomizing Approximate Quantum Encryption
A quantum encryption scheme (also called private quantum channel, or state
randomization protocol) is a one-time pad for quantum messages. If two parties
share a classical random string, one of them can transmit a quantum state to
the other so that an eavesdropper gets little or no information about the state
being transmitted. Perfect encryption schemes leak no information at all about
the message. Approximate encryption schemes leak a non-zero (though small)
amount of information but require a shorter shared random key. Approximate
schemes with short keys have been shown to have a number of applications in
quantum cryptography and information theory.
This paper provides the first deterministic, polynomial-time constructions of
quantum approximate encryption schemes with short keys. Previous constructions
(quant-ph/0307104) are probabilistic--that is, they show that if the operators
used for encryption are chosen at random, then with high probability the
resulting protocol will be a secure encryption scheme. Moreover, the resulting
protocol descriptions are exponentially long. Our protocols use keys of the
same length as (or better length than) the probabilistic constructions; to
encrypt qubits approximately, one needs bits of shared key.
An additional contribution of this paper is a connection between classical
combinatorial derandomization and constructions of pseudo-random matrix
families in a continuous space.Comment: 11 pages, no figures. In Proceedings of RANDOM 2004, Cambridge, MA,
August 200
A Decision-Support Framework For Using Value Capture to Fund Public Transit: Lessons From Project-Specific Analyses, Research Report 11-14
Local and state governments provide 75 percent of transit funds in the United States. With all levels of governments under significant fiscal stress, any new transit funding mechanism is welcome. Value capture (VC) is one such mechanism. Based on the “benefits received” principle, VC involves the identification and capture of public infrastructure-led increase in land value. While the literature has extensively demonstrated the property-value impacts of transit investments and has empirically simulated the potential magnitude of VC revenues for financing transit facilities, very little research has examined the suitability of VC mechanisms for specific transit projects. This report aims to fill this research gap by examining five VC mechanisms in depth: tax-increment financing (TIF), special assessment districts (SADs), transit impact fees, joint developments, and air rights. The report is intended to assist practitioners in gauging the legal, financial, and administrative suitability of VC mechanisms for meeting project-specific funding requirements
Wildlife tourism in Scotland – the example of grouse shooting
Wildlife tourism in Scotland has seen a recent increase in profile, with two reports providing new figures on the economic value of the activity. The reports, by the Scottish Government and Scottish Natural Heritage (SNH), seem likely to generate policy responses to further develop the sector
Bayesian Modelling of Direct and Indirect Effects of Marine Reserves on Fishes : A thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Statistics at Massey University, Albany, New Zealand.
This thesis reviews and develops modern advanced statistical methodology for
sampling and modelling count data from marine ecological studies, with specific applications
to quantifying potential direct and indirect effects of marine reserves on fishes in north
eastern New Zealand. Counts of snapper (Pagrus auratus: Sparidae) from baited underwater
video surveys from an unbalanced, multi-year, hierarchical sampling programme were
analysed using a Bayesian Generalised Linear Mixed Model (GLMM) approach, which
allowed the integer counts to be explicitly modelled while incorporating multiple fixed and
random effects. Overdispersion was modelled using a zero-inflated negative-binomial error
distribution. A parsimonious method for zero inflation was developed, where the mean of the
count distribution is explicitly linked to the probability of an excess zero. Comparisons of
variance components identified marine reserve status as the greatest source of variation in
counts of snapper above the legal size limit. Relative densities inside reserves were, on
average, 13-times greater than outside reserves.
Small benthic reef fishes inside and outside the same three reserves were surveyed to
evaluate evidence for potential indirect effects of marine reserves via restored populations of
fishery-targeted predators such as snapper. Sites for sampling were obtained randomly from
populations of interest using spatial data and geo-referencing tools in R—a rarely used
approach that is recommended here more generally to improve field-based ecological
surveys. Resultant multispecies count data were analysed with multivariate GLMMs
implemented in the R package MCMCglmm, based on a multivariate Poisson lognormal error
distribution. Posterior distributions for hypothesised effects of interest were calculated
directly for each species. While reserves did not appear to affect densities of small fishes,
reserve-habitat interactions indicated that some endemic species of triplefin (Tripterygiidae)
had different associations with small-scale habitat gradients inside vs outside reserves. These patterns were consistent with a behavioural risk effect, where small fishes may be more
strongly attracted to refuge habitats to avoid predators inside vs outside reserves.
The approaches developed and implemented in this thesis respond to some of the
major current statistical and logistic challenges inherent in the analysis of counts of
organisms. This work provides useful exemplar pathways for rigorous study design,
modelling and inference in ecological systems
A Decision-Support Framework For Using Value Capture to Fund Public Transit: Lessons From Project-Specific Analyses
Local and state governments provide 75 percent of transit funds in the United States. With all levels of governments under significant fiscal stress, any new transit funding mechanism is welcome. Value capture (VC) is one such mechanism. Based on the “benefits received” principle, VC involves the identification and capture of public infrastructure-led increase in land value. While the literature has extensively demonstrated the property-value impacts of transit investments and has empirically simulated the potential magnitude of VC revenues for financing transit facilities, very little research has examined the suitability of VC mechanisms for specific transit projects. This report aims to fill this research gap by examining five VC mechanisms in depth: tax-increment financing (TIF), special assessment districts (SADs), transit impact fees, joint developments, and air rights. The report is intended to assist practitioners in gauging the legal, financial, and administrative suitability of VC mechanisms for meeting project-specific funding requirements
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