13,321 research outputs found
Studies of control strategies for building integrated solar energy system
Research and development work on Building Integrated Solar Energy Systems (BISES) has become an area of growing interest, not only in New Zealand (NZ) but worldwide. This interest has led to a significant growth in the use of solar energy to provide heating and electricity generation. This paper presents the theoretical and experimental results of a novel building integrated solar hot water system developed using commercial long run roofing materials. This work shows that it is possible to achieve effective integration that maintains the aesthetics of the building and also provides useful thermal energy. The results of a 6.73m2 glazed domestic hot water systems are presented. The key design parameters of the Building Integrated Thermal (BIT) system were identified and implemented in a TRansient SYstem Simulation (TRNSYS) model. Validation results comparing the simulation in TRNSYS and real experimentation show that experimental and simulation responses are close to each other. The coupling of TRNSYS and Matlab/Simulink shows the possibility to use Matlab/Simulink for developing appropriate control strategies for BIT roofing systems. Preliminary Fuzzy Logic (FL) intelligent controller was implemented in a Fuzzy Integrated System (FIS) toolbox in a Matlab/Simulink model and linked into TRNSYS model. Further work is needed to identify and design advanced predictive control strategies for the Building Integrated Photovoltaic Thermal (BIPVT) solar system and determine how the performance can be optimized
Relative proximity of chromosome territories influences chromosome exchange partners in radiation-induced chromosome rearrangements in primary human bronchial epithelial cells
Copyright © 2013 The Authors. This article is made available through the Brunel Open Access Publishing Fund. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.Copyright © 2013 The Authors. It is well established that chromosomes exist in discrete territories (CTs) in interphase and are positioned in a cell-type specific probabilistic manner. The relative localisation of individual CTs within cell nuclei remains poorly understood, yet many cancers are associated with specific chromosome rearrangements and there is good evidence that relative territorial position influences their frequency of exchange. To examine this further, we characterised the complexity of radiation-induced chromosome exchanges in normal human bronchial epithelial (NHBE) cells by M-FISH analysis of PCC spreads and correlated the exchanges induced with their preferred interphase position, as determined by 1/2-colour 2D-FISH analysis, at the time of irradiation. We found that the frequency and complexity of aberrations induced were reduced in ellipsoid NHBE cells in comparison to previous observations in spherical cells, consistent with aberration complexity being dependent upon the number and proximity of damaged CTs, i.e. lesion proximity. To ask if particular chromosome neighbourhoods could be identified we analysed all radiation-induced pair-wise exchanges using SCHIP (statistics for chromosome interphase positioning) and found that exchanges between chromosomes (1;13), (9;17), (9;18), (12;18) and (16;21) all occurred more often than expected assuming randomness. All of these pairs were also found to be either sharing similar preferred positions in interphase and/or sharing neighbouring territory boundaries. We also analysed a human small cell lung cancer cell line, DMS53, by M-FISH observing the genome to be highly rearranged, yet possessing rearrangements also involving chromosomes (1;13) and (9;17). Our findings show evidence for the occurrence of non-random exchanges that may reflect the territorial organisation of chromosomes in interphase at time of damage and highlight the importance of cellular geometry for the induction of aberrations of varying complexity after exposure to both low and high-LET radiation.Department of Healt
Algebraic Approach to Interacting Quantum Systems
We present an algebraic framework for interacting extended quantum systems to
study complex phenomena characterized by the coexistence and competition of
different states of matter. We start by showing how to connect different
(spin-particle-gauge) {\it languages} by means of exact mappings (isomorphisms)
that we name {\it dictionaries} and prove a fundamental theorem establishing
when two arbitrary languages can be connected. These mappings serve to unravel
symmetries which are hidden in one representation but become manifest in
another. In addition, we establish a formal link between seemingly unrelated
physical phenomena by changing the language of our model description. This link
leads to the idea of {\it universality} or equivalence. Moreover, we introduce
the novel concept of {\it emergent symmetry} as another symmetry guiding
principle. By introducing the notion of {\it hierarchical languages}, we
determine the quantum phase diagram of lattice models (previously unsolved) and
unveil hidden order parameters to explore new states of matter. Hierarchical
languages also constitute an essential tool to provide a unified description of
phases which compete and coexist. Overall, our framework provides a simple and
systematic methodology to predict and discover new kinds of orders. Another
aspect exploited by the present formalism is the relation between condensed
matter and lattice gauge theories through quantum link models. We conclude
discussing applications of these dictionaries to the area of quantum
information and computation with emphasis in building new models of computation
and quantum programming languages.Comment: 44 pages, 14 psfigures. Advances in Physics 53, 1 (2004
The spirit of sport: the case for criminalisation of doping in the UK
This article examines public perceptions of doping in sport, critically evaluates the effectiveness of current anti-doping sanctions and proposes the criminalisation of doping in sport in the UK as part of a growing global movement towards such criminalisation at national level. Criminalising doping is advanced on two main grounds: as a stigmatic deterrent and as a form of retributive punishment enforced through the criminal justice system. The ‘spirit of sport’ defined by the World Anti-Doping Agency (WADA) as being based on the values of ethics, health and fair-play is identified as being undermined by the ineffectiveness of existing anti-doping policy in the current climate of doping revelations, and is assessed as relevant to public perceptions and the future of sport as a whole. The harm-reductionist approach permitting the use of certain performance enhancing drugs (PEDs) is considered as an alternative to anti-doping, taking into account athlete psychology, the problems encountered in containing doping in sport through anti-doping measures and the effect of these difficulties on the ‘spirit of sport’. This approach is dismissed in favour of criminalising doping in sport based on the offence of fraud. It will be argued that the criminalisation of doping could act as a greater deterrent than existing sanctions imposed by International Federations, and, when used in conjunction with those sanctions, will raise the overall ‘price’ of doping. The revelations of corruption within the existing system of self-governance within sport have contributed to a disbelieving public and it will be argued that the criminalisation of doping in sport could assist in satisfying the public that justice is being done and in turn achieve greater belief in the truth of athletic performances
Exact Spectrum of SU(n) Spin Chain with Inverse-Square Exchange
The spectrum and partition function of a model consisting of SU(n) spins
positioned at the equilibrium positions of a classical Calogero model and
interacting through inverse-square exchange are derived. The energy levels are
equidistant and have a high degree of degeneracy, with several SU(n) multiplets
belonging to the same energy eigenspace. The partition function takes the form
of a q-deformed polynomial. This leads to a description of the system by means
of an effective parafermionic hamiltonian, and to a classification of the
states in terms of "modules" consisting of base-n strings of integers.Comment: 12 pages, CERN-TH-7040/9
Exclusion statistics: A resolution of the problem of negative weights
We give a formulation of the single particle occupation probabilities for a
system of identical particles obeying fractional exclusion statistics of
Haldane. We first derive a set of constraints using an exactly solvable model
which describes an ideal exclusion statistics system and deduce the general
counting rules for occupancy of states obeyed by these particles. We show that
the problem of negative probabilities may be avoided with these new counting
rules.Comment: REVTEX 3.0, 14 page
Alpha-particle-induced complex chromosome exchanges transmitted through extra-thymic lymphopoiesis in vitro show evidence of emerging genomic instability
Human exposure to high-linear energy transfer α-particles includes environmental (e.g. radon gas and its decay progeny), medical (e.g. radiopharmaceuticals) and occupational (nuclear industry) sources. The associated health risks of α-particle exposure for lung cancer are well documented however the risk estimates for leukaemia remain uncertain. To further our understanding of α-particle effects in target cells for leukaemogenesis and also to seek general markers of individual exposure to α-particles, this study assessed the transmission of chromosomal damage initially-induced in human haemopoietic stem and progenitor cells after exposure to high-LET α-particles. Cells surviving exposure were differentiated into mature T-cells by extra-thymic T-cell differentiation in vitro. Multiplex fluorescence in situ hybridisation (M-FISH) analysis of naïve T-cell populations showed the occurrence of stable (clonal) complex chromosome aberrations consistent with those that are characteristically induced in spherical cells by the traversal of a single α-particle track. Additionally, complex chromosome exchanges were observed in the progeny of irradiated mature T-cell populations. In addition to this, newly arising de novo chromosome aberrations were detected in cells which possessed clonal markers of α-particle exposure and also in cells which did not show any evidence of previous exposure, suggesting ongoing genomic instability in these populations. Our findings support the usefulness and reliability of employing complex chromosome exchanges as indicators of past or ongoing exposure to high-LET radiation and demonstrate the potential applicability to evaluate health risks associated with α-particle exposure.This work was supported by the Department of Health, UK. Contract RRX95 (RMA NSDTG)
Shadow band in the one-dimensional large Hubbard model
We show that the factorized wave-function of Ogata and Shiba can be used to
calculate the dependent spectral functions of the one-dimensional, infinite
Hubbard model, and of some extensions to finite . The resulting spectral
function is remarkably rich: In addition to low energy features typical of
Luttinger liquids, there is a well defined band, which we identify as the
shadow band resulting from spin fluctuations. This band should be
detectable experimentally because its intensity is comparable to that of the
main band for a large range of momenta.Comment: Latex file. 4 pages. Figures upon reques
Testing Newtonian Gravity with AAOmega: Mass-to-Light Profiles of Four Globular Clusters
Testing Newtonian gravity in the weak-acceleration regime is vital to our
understanding of the nature of the gravitational interaction. It has recently
been claimed that the velocity dispersion profiles of several globular clusters
flatten out at large radii, reminiscent of galaxy rotation curves, even though
globular clusters are thought to contain little or no dark matter. We
investigate this claim, using AAOmega observations of four globular clusters,
namely M22, M30, M53 and M68. M30, one such cluster that has had this claim
made for its velocity dispersion, was included for comparison with previous
studies. We find no statistically significant flattening of the velocity
dispersion at large radii for any of our target clusters and therefore we infer
the observed dynamics do not require that globular clusters are dark matter
dominated, or a modification of gravity. Furthermore, by applying a simple
dynamical model we determine the radial mass-to-light profiles for each
cluster. The isothermal rotations of each cluster are also measured, with M22
exhibiting clear rotation, M68 possible rotation and M30 and M53 lacking any
rotation, within the uncertainties.Comment: 7 pages, 4 figures and two tables. Accepted by MNRA
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