Phase transition and spin-wave dispersion in quantum Hall bilayers at filling factor nu=1

We present an effective Hamiltonian for a bilayer quantum Hall system at filling factor $\nu=1$ neglecting charge fluctuations. Our model is formulated in terms of spin and pseudospin operators and is an exact representation of the system within the above approximation. We analyze its low-lying excitations in terms of spin-wave theory. Moreover we add to previous first-principle exact-diagonalization studies concentrating on the quantum phase transition seen in this system.Comment: Four pages, proceedings for EP2DS-14, Prague 200

Environmental Impacts of Multi-Storey Buildings Using Different Construction Materials

The Research Goals and Objectives for this project were set out in the Ministry of Agriculture and Forestry (MAF) RFP POR/7811, April 2007. The University of Canterbury responded with a collaborative research programme ‘to fill the information gap about what is the greatest amount of wood that can be used in the construction and fit-out of commercial, large-scale buildings in New Zealand (and) …… to provide Life Cycle Assessment (LCA) information about the benefits of maximising the use of wood in sustainable buildings’. This research project modelled the performance of four similar office building designs – Concrete, Steel, Timber and TimberPlus – all based on an actual six-storey 4,200m2 building, to investigate the influence of construction materials on life cycle energy use and global warming potential (GWP). All four buildings were designed for a 60 year lifetime, with very similar low operational energy consumption. The Concrete and Steel buildings employed conventional structural design and construction methods. The Timber buildings were designed with an innovative post-tensioned timber structure using laminated veneer lumber (LVL). The TimberPlus design further increased the use of timber in architectural features such as exterior cladding, windows and ceilings. All timber materials are renewable and durable, sourced from sustainably managed forests. Predicted construction times for all four buildings are similar. The LCA study by Scion considered the full life cycle of the buildings including initial embodied energy of the materials, and maintenance, transport, operational energy and two endof- life scenarios, where deconstructed materials were either landfilled or reutilised. Increasing the amount of timber in the buildings decreased the initial embodied energy and GWP of materials and also decreased the total energy consumption and GWP over the 60 year lifetime. The TimberPlus design clearly had the lowest environmental impacts, whilst the Steel building had the highest impacts. A significant benefit could be obtained in the Steel, Concrete and Timber buildings by replacing high embodied energy components (especially aluminium windows and louvres) with timber. The final destination of deconstruction waste at the end of the 60 year life-cycle is extremely important. Landfilling of timber waste, with the permanent storage of most of the carbon in the timber, was slightly more beneficial than burning of wood waste for energy. The benefits of landfilling timber waste will increase as modern and future landfill construction and management capture and utilise more of the methane generated by decomposition. Recycling of steel and concrete is more beneficial than landfilling. It is important to note that looking at a single environmental indicator, such as GWP, could lead to unintended outcomes. For example, for the TimberPlus building the landfilling scenario would be slightly better in terms of climate change. However, looking at the energy results alongside the GWP results, the reutilisation scenario shows both an energy reutilisation benefit, as well as still being beneficial to climate change. Therefore, the use of multiple indicators may be necessary to inform the environmental decision-making process.An alternative end-of-life scenario which assumed permanent storage of carbon in wood materials showed that net total GWP for the materials in the TimberPlus building is negative, because the long-term storage of over 630 tonnes of carbon dioxide removed from the atmosphere more than cancels out all the greenhouse gases emitted in the manufacture of all the other building materials. In this scenario, the TimberPlus building could be considered to be ‘carbon-neutral’ for at least the first 12 years of its operation. With NZ-specific energy and GWP coefficients now available, a simple model can be developed for assessing the energy and GWP impacts of individual buildings. This study shows that the Green Star Office rating tool does not capture all the benefits of using more wood in buildings which are identified by the simple model or a full LCA study. Support of on-going research is essential to further develop the potential for Timber buildings to be more widely used in NZ, with subsequent reductions in greenhouse gas emissions

Metabolic syndrome in polycystic ovary syndrome

Zespół metaboliczny (MS, metabolic syndrome) i zespół policystycznych jajników (PCOS, polycystic ovary syndrome) są często rozpoznawanymi zaburzeniami u kobiet. Częstość występowania zespołu metabolicznego u kobiet z PCOS zależy od zastosowanych kryteriów diagnostycznych. W prezentowanej pracy autorzy rozważają tezę, że przyczyną obu zaburzeń może być insulinooporność, będąca następstwem otyłości brzusznej. Ponadto dokonują przeglądu literatury dotyczącej występowania MS u kobiet z PCOS oraz omawiają wpływ wyboru określonych kryteriów diagnostycznych MS i PCOS na oszacowanie czêstoœci ich występowania.Both metabolic syndrome (MS) and polycystic ovary syndrome (PCOS) are common among women. The exact prevalence of MS in women with PCOS is dependent upon the diagnostic criteria used for each. However, the frequent co-occurrence of both MS and PCOS in women is suggestive of a common aetiology. In this short review article we argue that insulin resistance, as a consequence of abdominal obesity, may represent such a common aetiology. We also review the literature on the prevalence of MS in women with PCOS and consider the impact that the particular criteria used to diagnose both MS and PCOS may have had on these estimates of prevalence

Decline and Fall of the Standard Model?

Motivations for physics beyond the Standard Model are reviewed, with particular emphasis on supersymmetry at the TeV scale. Constraints on the minimal supersymmetric extension of the Standard Model with universal soft supersymmetry-breaking terms (CMSSM) are discussed. These are also combined with the supersymmetric interpretation of the anomalous magnetic moment of the muon. The prospects for observing supersymmetry at accelerators are reviewed using benchmark scenarios to focus the discussion. Prospects for other experiments are discussed, including the detection of cold dark matter, mu -> e gamma and related processes, as well as proton decay.Comment: Invited talk at 20th International Symposium on Lepton and Photon Interactions at High Energies, Rome, 2001, 16 pages LaTeX, 13 eps figures, uses special .cls file (included

Adapting the Scar-in-a-Jar to Skin Fibrosis and Screening Traditional and Contemporary Anti-Fibrotic Therapies

Skin fibrosis still constitutes an unmet clinical need. Although pharmacological strategies are at the forefront of scientific and technological research and innovation, their clinical translation is hindered by the poor predictive capacity of the currently available in vitro fibrosis models. Indeed, customarily utilised in vitro scarring models are conducted in a low extracellular matrix milieu, which constitutes an oxymoron for the in-hand pathophysiology. Herein, we coupled macromolecular crowding (enhances and accelerates extracellular matrix deposition) with transforming growth factor beta 1 (TGF beta 1; induces trans-differentiation of fibroblasts to myofibroblasts) in human dermal fibroblast cultures to develop a skin fibrosis in vitro model and to screen a range of anti-fibrotic families (corticosteroids, inhibitors of histone deacetylases, inhibitors of collagen crosslinking, inhibitors of TGF beta 1 and pleiotropic inhibitors of fibrotic activation). Data obtained demonstrated that macromolecular crowding combined with TGF beta 1 significantly enhanced collagen deposition and myofibroblast transformation. Among the anti-fibrotic compounds assessed, trichostatin A (inhibitors of histone deacetylases); serelaxin and pirfenidone (pleiotropic inhibitors of fibrotic activation); and soluble TGF beta receptor trap (inhibitor of TGF beta signalling) resulted in the highest decrease of collagen type I deposition (even higher than triamcinolone acetonide, the gold standard in clinical practice). This study further advocates the potential of macromolecular crowding in the development of in vitro pathophysiology models.Peer reviewe

Hard-core Yukawa model for two-dimensional charge stabilized colloids

The hyper-netted chain (HNC) and Percus-Yevick (PY) approximations are used to study the phase diagram of a simple hard-core Yukawa model of charge-stabilized colloidal particles in a two-dimensional system. We calculate the static structure factor and the pair distribution function over a wide range of parameters. Using the statics correlation functions we present an estimate for the liquid-solid phase diagram for the wide range of the parameters.Comment: 7 pages, 9figure

Comparing genomic signatures of selection between the Abbassa Strain and eight wild populations of Nile tilapia (Oreochromis niloticus) in Egypt

Domestication to captive rearing conditions, along with targeted selective breeding have genetic consequences that vary from those in wild environments. Nile tilapia (Oreochromis niloticus) is one of the most translocated and farmed aquaculture species globally, farmed throughout Asia, North and South America, and its African native range. In Egypt, a breeding program established the Abbassa Strain of Nile tilapia (AS) in 2002 based on local broodstock sourced from the Nile River. The AS has been intensively selected for growth and has gone through genetic bottlenecks which have likely shifted levels and composition of genetic diversity within the strain. Consequently, there are questions on the possible genetic impact AS escapees may have on endemic populations of Nile tilapia. However, to date there have been no genetic studies comparing genetic changes in the domesticated AS to local wild populations. This study used 9,827 genome-wide SNPs to investigate population genetic structure and signatures of selection in the AS (generations 9–11) and eight wild Nile tilapia populations from Egypt. SNP analyses identified two major genetic clusters (captive and wild populations), with wild populations showing evidence of isolation-by-distance among the Nile Delta and upstream riverine populations. Between genetic clusters, approximately 6.9% of SNPs were identified as outliers with outliers identified on all 22 O. niloticus chromosomes. A lack of localized outlier clustering on the genome suggests that no genes of major effect were presently detected. The AS has retained high levels of genetic diversity (Ho_All = 0.21 ± 0.01; He_All = 0.23 ± 0.01) when compared to wild populations (Ho_All = 0.18 ± 0.01; He_All = 0.17 ± 0.01) after 11 years of domestication and selective breeding. Additionally, 565 SNPs were unique within the AS line. While these private SNPs may be due to domestication signals or founder effects, it is suspected that introgression with blue tilapia (Oreochromis aureus) has occurred. This study highlights the importance of understanding the effects of domestication in addition to wild population structure to inform future management and dissemination decisions. Furthermore, by conducting a baseline genetic study of wild populations prior to the dissemination of a domestic line, the effects of aquaculture on these populations can be monitored over time

Development and Application of 3-Dimensional Transmission Electron Microscopy (3D-TEM) for the Characterization of Metal-Zeolite Catalyst Systems

With electron tomography (3D-TEM) a 3D-reconstruction is calculated from a series of TEM images taken at a tilt angle range (tilting range) of +70° to -70°. The reconstruction can be visualized with contour surfaces that give information about the surface of the sample as well as with slices through the reconstruction that give detailed information on the interior of the sample. Electron tomography gives much more information than Scanning Electron Microscopy (SEM), since SEM gives only information about the surface of a sample. As a case study, the imaging of silver clusters on zeolite NaY is given. The reconstruction shows silver particles at the external surface as well as a silver particle in a mesopore of the zeolite crystallite. It is concluded that 3D-TEM comprises a breakthrough in the characterization of nano-structured solid catalysts