An auralisation method for real time subjective testing of modal parameters.

Subjective testing is necessary when attempting to determine the human response to audio quality. Small rooms, such as recording studio control rooms themselves have an effect upon the quality of the perceived audio reproduction. Of particular interest is the low frequency region where resonances, or ‘room modes’, occur. It is necessary to test a number of modal parameters individually and be able to alter them instantly during testing in response to listener perception. An auralisation method has been developed which is used to compare musical samples within modelled rooms. Methods are discussed in the context of providing a practical system, where real time testing is feasible. The formation of the room’s transfer function is discussed, as are a number of issues relating to the generation of audio samples. This work is then placed in context with a brief explanation of how the system is to be used in a real subjective test

The complete set of infinite volume ground states for Kitaev's abelian quantum double models

We study the set of infinite volume ground states of Kitaev's quantum double model on $\mathbb{Z}^2$ for an arbitrary finite abelian group $G$. It is known that these models have a unique frustration-free ground state. Here we drop the requirement of frustration freeness, and classify the full set of ground states. We show that the ground state space decomposes into $|G|^2$ different charged sectors, corresponding to the different types of abelian anyons (also known as superselection sectors). In particular, all pure ground states are equivalent to ground states that can be interpreted as describing a single excitation. Our proof proceeds by showing that each ground state can be obtained as the weak$^*$ limit of finite volume ground states of the quantum double model with suitable boundary terms. The boundary terms allow for states which represent a pair of excitations, with one excitation in the bulk and one pinned to the boundary, to be included in the ground state space.Comment: 27 pages, 6 figures. v2: minor corrections, some simplifications and clarificactions adde

Perceptual thresholds for the effects of room modes as a function of modal decay

Room modes cause audible artefacts in listening environments. Modal control approaches have emerged in scientific literature over the years and, often, their performance is measured by criteria that may be perceptually unfounded. Previous research has shown modal decay as a key perceptual factor in detecting modal effects. In this work, perceptual thresholds for the effects of modes as a function of modal decay have been measured in the region between 32Hz and 250Hz. A test methodology has been developed to include modal interaction and temporal masking from musical events, which are important aspects in recreating an ecologically valid test regime. This method has been deployed in addition to artificial test stimuli traditionally used in psychometric studies, which provide unmasked, absolute thresholds. For artificial stimuli, thresholds decrease monotonically from 0.9 seconds at 32 Hz to 0.17 seconds at 200 Hz, with a knee at 63 Hz. For music stimuli, thresholds decrease monotonically from 0.51 seconds at 63 Hz to 0.12 seconds at 250 Hz. Perceptual thresholds are shown to be dependent on frequency and to a much lesser extent on level. Results presented here define absolute and practical thresholds, which are useful as perceptually relevant optimization targets for modal control methods

Tracking ancient beach-lines inland: 2600-year-old dentate-stamped ceramics at Hopo, Vailala River region, Papua New Guinea

The Lapita expansion took Austronesian seafaring peoples with distinctive pottery eastward from the Bismarck Archipelago to western Polynesia during the late second millennium BC, marking the first stage in the settlement of Oceania. Here it is shown that a parallel process also carried Lapita pottery and people many hundreds of kilometres westward along the southern shore of Papua New Guinea. The key site is Hopo, now 4.5km inland owing to the progradation of coastal sand dunes, but originally on the sea edge. Pottery and radiocarbon dates indicate Lapita settlement in this location c.600 BC, and suggest that the long-distance maritime networks linking the entire southern coast of Papua New Guinea in historical times may trace their origin to this period

Churches Partnering Together : Biblical Strategies for Fellowship, Evangelism, and Compassion

Most churches in the United States have fewer than 75 members. Many of these congregations barely have enough money to pay their pastor’s salary, let alone launch a movement or host a conference. How can they hope to make an impact beyond their own walls? In Churches Partnering Together, Chris Bruno and Matt Dirks show how all churches—big and small—can do more together than they can do apart. Looking to the New Testament for guidance, this practical book will help pastors, church leaders, and laypeople alike think creatively about gospel-driven church partnerships in their own communities and around the world.https://digitalcommons.cedarville.edu/faculty_books/1177/thumbnail.jp

On the stability of charges in infinite quantum spin systems

We consider a theory of superselection sectors for infinite quantum spin systems, describing charges that can be approximately localized in cone-like regions. The primary examples we have in mind are the anyons (or charges) in topologically ordered models such as Kitaev's quantum double models and perturbations of such models. In order to cover the case of perturbed quantum double models, the Doplicher-Haag-Roberts approach, in which strict localization is assumed, has to be amended. To this end we consider endomorphisms of the observable algebra that are almost localized in cones. Under natural conditions on the reference ground state (which plays a role analogous to the vacuum state in relativistic theories), we obtain a braided tensor $C^*$-category describing the sectors. We also introduce a superselection criterion selecting excitations with energy below a threshold. When the threshold energy falls in a gap of the spectrum of the ground state, we prove stability of the entire superselection structure under perturbations that do not close the gap. We apply our results to prove that all essential properties of the anyons in Kitaev's abelian quantum double models are stable against perturbations.Comment: v2: 40 pages. Improved presentation, some corrections. v1: 37 pages. Some results were first reported in the dissertation of MC, arXiv:1708.0503