### Recent Submissions

Superfluid helium droplets have emerged as a new route for the fabrication of nanomaterials. They are large clusters of helium that allow molecules/atoms to be added and subsequently aggregate, providing a confined environment for growing nanometer-sized entities with exotic properties. For droplets composed of less than 107 helium atoms, small particles with diameters no more than 10 nm can be grown. In larger helium droplets quantized vortices play an important role, leading to the aggregat...

Ellis, Andrew M.; Yang, Shengfu

The Domain Name System (DNS) is one of the most important components of the Internet infrastructure. DNS relies on a delegation-based architecture, where resolution of names to their IP addresses requires resolving the names of the servers responsible for those names. The recursive structures of the inter dependencies that exist between name servers associated with each zone are called dependency graphs. System administrators' operational decisions have far reaching effects on the DNSs qualit...

Radwan, Marwan; Heckel, Reiko

Studies of the rotation of disk galaxies have long been used to infer the presence and distribution of dark matter within them. Here I present a new Markov Chain Monte Carlo (MCMC) method to explore the extensive and complex parameter space created by the possible combinations of dark and luminous matter in these galaxies. I present exhaustive testing of this method to ensure it can retrieve dark matter halo parameters from artificial data, and apply it to real galaxies from The HI Nearb...

Hague, Peter R.

Blueshifted AGN absorption lines indicate outflowing material from the central engine. Many repeat spectral observations of AGN have observed variability in the shape and strength of these lines, however there is no scientific consensus regarding the dominant mechanism which drives this variability. The main purpose of this thesis is to investigate this mechanism in a sample of BALQSOs and a Seyfert 1 galaxy. The BALQSO sample consists of 50 quasars, in which we test the dependence of br...

Wildy, Conor

The goal of this research was to use weather parameters to compute refractivity variation of the atmosphere that can be used to predict refractivity distribution in the first kilometre of the atmosphere over the English Channel for UHF and VHF propagation and to understand the influence of meteorology on propagation. Different refractivity profiles are constructed based on meteorological data taken from the UK Meteorological Office in order to investigate their effects on wave propagation. Th...

Alam, Imtiaz

We study the descriptive complexity of parity games by taking into account the coloring of their game graphs whilst ignoring their ownership structure. Colored game graphs are identified if they determine the same winning regions and strategies, for all ownership structures of nodes. The Rabin index of a parity game is the minimum of the maximal color taken over all equivalent coloring functions. We show that deciding whether the Rabin index is at least k is in PTIME for k=1 but NP-hard for a...

Huth, M; Kuo, JHP; Piterman, N

The taxonomy of benthic foraminifera recovered from 160 core samples over depth 20.59 m and representing the past ~597 Kyr (sedimentary deposit of the Tarantian and Ionian stages) at Bowers Ridge, Bering Sea IODP site U1342, includes some 52 species from 41 genera and 22 families: these species are given formal taxonomic treatment with detailed illustration. A further 16 species are discussed in open nomenclature. Foraminifer assemblages are dominated by species of Takayanagia delicata, ...

Oluyemi, Aturamu Adeyinka

We recently introduced p-automata, automata that read discrete-time Markov chains. We used turn-based stochastic parity games to define acceptance of Markov chains by a subclass of p-automata. Definition of acceptance required a cumbersome and complicated reduction to a series of turn-based stochastic parity games. The reduction could not support acceptance by general p-automata, which was left undefined as there was no notion of games that supported it. Here we generalize two-player gam...

Piterman, Nir; Chatterjee, Krishnendu

Attractors in parity games are a technical device for solving "alternating" reachability of given node sets. A well known solver of parity games - Zielonka's algorithm - uses such attractor computations recursively. We here propose new forms of attractors that are monotone in that they are aware of specific static patterns of colors encountered in reaching a given node set in alternating fashion. Then we demonstrate how these new forms of attractors can be embedded within greatest fixed-point...

Huth, M.; Kuo, J. H. P.; Piterman, Nir

We investigate the variability behaviour of the broad H β emission-line to driving continuum variations in the best-studied AGN NGC 5548. For a particular choice of broad emission-line region (BLR) geometry, H β surface emissivity based on photoionization models, and using a scaled version of the 13-yr optical continuum light-curve as a proxy for the driving ionizing continuum, we explore several key factors that determine the broad emission-line luminosity L, characteristic size RRW, and var...

Goad, Michael R.; Korista, K. T.

In this work we discuss the problem of selecting suitable approximators from families of parameterized elementary functions that are known to be dense in a Hilbert space of functions. We consider and analyze published procedures, both randomized and deterministic, for selecting elements from these families that have been shown to ensure the rate of convergence in L2 norm of order O(1/N), where N is the number of elements. We show that both randomized and deterministic procedures are successfu...

Gorban, Alexander N.; Tyukin, Ivan Yu.; Prokhorov, D. V.; Sofeikov, Konstantin I.

Aspect-orientation is a relatively new paradigm that introduces abstractions to modularize the implementation of system-wide policies. It is based on a composition operation, called aspect weaving, that implicitly modifies a base system by performing related changes within the system modules. Aspect-oriented graph grammars (AOGG) extend the classic graph grammar formalism by defining aspects as sets of rule-based modifications over a base graph grammar. Despite the advantages of aspect-orient...

Machado, Rodrigo; Heckel, Reiko; Ribeiro, Leila

Linear logics have been shown to be able to embed both rewriting-based approaches and process calculi in a single, declarative framework. In this paper we are exploring the embedding of double-pushout graph transformations into quantified linear logic, leading to a Curry-Howard style isomorphism between graphs and transformations on one hand, formulas and proof terms on the other. With linear implication representing rules and reachability of graphs, and the tensor modelling parallel composit...

Torrini, Paolo; Heckel, Reiko

In situ neutron diffraction has been used to investigate the deformation behaviour of extruded magnesium at room temperature, -100 °C and 150 °C. Significant differences in the active twinning/slip systems, attributed to the strong crystallographic texture and temperature dependence, were observed. Twining is the dominant deformation mode during the cyclic loading at room temperature and at cryogenic temperature. In contrast, at high temperature, additional slip planes were activated and redu...

Zhang, S. Y.; Hainsworth, Sarah V.; Lawes, Simon D.A.

A regolith map for the Lawra Belt has been developed by categorizing the regolith-landform units by processing and interpreting remote sensing data. Regolith landform units were extracted from Landsat band ratios 3/1 and 5/4 to map ferruginous saprolite and lags; band ratio 5/7 was used to identify residual regolith and band ratio 4/2 was employed to separate ferruginous units from non-ferruginous regolith. Additional regolith landform units’ discrimination was provided by compiling and inter...

Arhin, E.; Jenkin, Gawen R. T.; Cunningham, W. D.; Nude, P.

In this paper we revisit Safra's determinization constructions. We show how to construct deterministic automata with fewer states and, most importantly, parity acceptance conditions. Specifically, starting from a nondeterministic Buchi automaton with n states our construction yields a deterministic parity automaton with n2n+2 states and index 2n (instead of a Rabin automaton with (12)nn2n states and n pairs). Starting from a nondeterministic Streett automaton with n states and k pairs our con...

Piterman, Nir

C. elegans vulval development is one of the best-characterized systems to study cell fate specification during organogenesis. The detailed knowledge of the signaling pathways determining vulval precursor cell (VPC) fates permitted us to create a computational model based on the antagonistic interactions between the epidermal growth factor receptor (EGFR)/RAS/MAPK and the NOTCH pathways that specify the primary and secondary fates, respectively. A key notion of our model is called bounded asyn...

Nusser-Stein, Stefanie; Beyer, Antje; Rimann, Ivo; Adamczyk, Magdalene; Piterman, Nir... et al.

We consider the offline sorting buffer problem. The input is a sequence of items of different types. All items must be processed one by one by a server. The server is equipped with a random-access buffer of limited capacity which can be used to rearrange items. The problem is to design a scheduling strategy that decides upon the order in which items from the buffer are sent to the server. Each type change incurs unit cost, and thus, the cost minimizing objective is to minimize the total numbe...

Chan, Ho-Leung; Megow, Nicole; Stee, Rob van; Sitters, Rene

Large Eddy Simulation is used to simulate a series of plane mixing layers. The influence of the spanwise domain on the development of the mixing layer, and the evolution of the coherent structures, are considered. The mixing layers originate from laminar conditions, and an idealised inflow condition is found to produce accurate flow predictions when the spanwise computational domain extent is sufficient to avoid confinement effects. Spanwise domain confinement of the flow occurs when the rati...

McMullan, William A.

The Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) provides measurements over the wavelength range 5 to 28.5 μm. MIRI has, within a single “package,” four key scientific functions: photometric imaging, coronagraphy, single-source low-spectral resolving power (R ∼ 100) spectroscopy, and medium-resolving power (R ∼ 1500 to 3500) integral field spectroscopy. An associated cooler system maintains MIRI at its operating temperature of < 6.7 K. This paper describes the drivi...

Wright, GS; Wright, D; Goodson, GB; Rieke, GH; Aitink-Kroes, G... et al.

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