Moduli Corrections to Gauge and Gravitational Couplings in four dimensional Superstrings

We study one-loop, moduli-dependent corrections to gauge and gravitational couplings in supersymmetric vacua of the heterotic string. By exploiting their relation to the integrability condition for the associated CP-odd couplings, we derive general expressions for them, both for $(2,2)$ and $(2,0)$ models, in terms of tree level four-point functions in the internal $N=2$ superconformal theory. The $(2,2)$ case, in particular symmetric orbifolds, is discussed in detail.Comment: 19 page

Modelling the local and global cloud formation on HD 189733b

Context. Observations suggest that exoplanets such as HD 189733b form clouds in their atmospheres which have a strong feedback onto their thermodynamical and chemical structure, and overall appearance. Aims. Inspired by mineral cloud modelling efforts for Brown Dwarf atmospheres, we present the first spatially varying kinetic cloud model structures for HD 189733b. Methods. We apply a 2-model approach using results from a 3D global radiation-hydrodynamic simulation of the atmosphere as input for a detailed, kinetic cloud formation model. Sampling the 3D global atmosphere structure with 1D trajectories allows us to model the spatially varying cloud structure on HD 189733b. The resulting cloud properties enable the calculation of the scattering and absorption properties of the clouds. Results. We present local and global cloud structure and property maps for HD 189733b. The calculated cloud properties show variations in composition, size and number density of cloud particles which are strongest between the dayside and nightside. Cloud particles are mainly composed of a mix of materials with silicates being the main component. Cloud properties, and hence the local gas composition, change dramatically where temperature inversions occur locally. The cloud opacity is dominated by absorption in the upper atmosphere and scattering at higher pressures in the model. The calculated 8{\mu}m single scattering Albedo of the cloud particles are consistent with Spitzer bright regions. The cloud particles scattering properties suggest that they would sparkle/reflect a midnight blue colour at optical wavelengths.Comment: Accepted for publication (A&A) - 21/05/2015 (Low Resolution Maps

Limits on extra dimensions in orbifold compactifications of superstrings

Perturbative breaking of supersymmetry in four-dimensional string theories predict in general the existence of new large dimensions at the TeV scale. Such dimensions can be consistent with perturbative unification up to the Planck scale in a class of string models and open the exciting possibility of lowering a part of the massive string spectrum at energies accessible to future accelerators. The main signature is the production of Kaluza-Klein excitations which have a very particular structure, strongly correlated with the supersymmetry breaking mechanism. We present a model independent analysis of the physics of these states in the context of orbifold compactifications of the heterotic superstring. In particular, we compute the limits on the size of large dimensions used to break supersymmetry.Comment: 16 pages, CPTH-A257.079

Rapid Prototyping Using 3-D Welding

Rapid prototyping systems are based, almost exclusively on polymer, or paper materials. The dimensions of the parts produced are limited by the volume of the processing area within the machine, and parts tend to warp or distort due to shrinkage and lack of support. Also the mechanical properties of the part are restricted to those of the processable materials and thus, in many cases, required 'engineering properties' cannot be obtainedMechanical Engineerin

What is the Value of Home? NOT FOR SALE - West End Interventions

Many Australians today are image consumers. We fail to question the importance of lifestyle imagery created and promoted by Real Estate Agencies whom have no actual part in the physical creation of house, or indeed the intimate making of "home" through our experiences of place. Real Estate Markets dictate how, where, when and what we buy. Re-sale values, profit-making, and value-adding interfere with the crafting of a home over time as a tangible, individual, collaborative, and rich lived experience of dwelling. The "NOT FOR SALE" project is a response and critique of the dominance of real estate forces in West End within the context and unshakable presence of a booming inner-city property market. This proposal originated from an experimental dwelling in Avebury St., West End. This project has been fashioned over a period of several years primarily from recycled local materials, interconnected with the changing needs and spatial requirements of the occupants and project participants. The influence of property markets is of little concern in this home "making". The "NOT FOR SALE" project attempts to question and critique the purely financial value that we as a society place upon our homes. By appropriating and re-coding the Real Estate Signage typologies, we aim to provoke social commentary on the dominance of real estate forces in the West End suburb. There is a strong and rich tradition of anti-consumerist activist graffiti in West End. Activists re-code signs and property with political commentary and critique. The "NOT FOR SALE" project draws upon this tradition through our RRESign (Recodified Real Estate Signs): we aim to redress the dominant commercial forces associated with the single house/property. Collectively, at the scale of the street, these RRESigns will reflect a critique of street scale, amenity, and character. Finally, at the scale of the suburb, the network of RRESigns will reflect a critique of the idea of place making. Collectively, the aim of the "NOT FOR SALE" RRESign interventions is to highlight the idea of making and the material characteristics of dwelling that challenges the cultural value of commodified property, re-defining and prioritising the idea of "home". Conventional Real Estate signs use images and text to sell an idea of home: our proposed interventions sell nothing, and are rather celebrations of the joy of making tactile, handcrafted objects, and by extension, the making and crafting of home. The intimate and experiential understanding of home will be harnessed through the engagement of local residents. Community groups within West End such as Local Push can further disseminate the RRESign interventions. The signs will be constructed West End-specific materials (old signs purchased from inexpensive second-hand material merchant Reverse Garbage in Montague Rd.): turning post-consumer waste into objects of material beauty and social critique. Residents and community groups will be encouraged to place their RRESigns outside their properties and adjacent real estate signs, frustrating and recoding the existing For-Sale signs that currently dominate the West End street scape. The project is dependent on the support of the local residents, extending from a few signs in Avebury St. to a network of RRESigns throughout West End. A commentary on people's responses to the project will be linked to the www.apbv.com.au website. What is the value of home

Spinning test particles and clock effect in Schwarzschild spacetime

We study the behaviour of spinning test particles in the Schwarzschild spacetime. Using Mathisson-Papapetrou equations of motion we confine our attention to spatially circular orbits and search for observable effects which could eventually discriminate among the standard supplementary conditions namely the Corinaldesi-Papapetrou, Pirani and Tulczyjew. We find that if the world line chosen for the multipole reduction and whose unit tangent we denote as $U$ is a circular orbit then also the generalized momentum $P$ of the spinning test particle is tangent to a circular orbit even though $P$ and $U$ are not parallel four-vectors. These orbits are shown to exist because the spin induced tidal forces provide the required acceleration no matter what supplementary condition we select. Of course, in the limit of a small spin the particle's orbit is close of being a circular geodesic and the (small) deviation of the angular velocities from the geodesic values can be of an arbitrary sign, corresponding to the possible spin-up and spin-down alignment to the z-axis. When two spinning particles orbit around a gravitating source in opposite directions, they make one loop with respect to a given static observer with different arrival times. This difference is termed clock effect. We find that a nonzero gravitomagnetic clock effect appears for oppositely orbiting both spin-up or spin-down particles even in the Schwarzschild spacetime. This allows us to establish a formal analogy with the case of (spin-less) geodesics on the equatorial plane of the Kerr spacetime. This result can be verified experimentally.Comment: IOP macros, eps figures n. 2, to appear on Classical and Quantum gravity, 200

Critical velocity ionisation in substellar atmospheres

The observation of radio, X-ray and Hα emission from substellar objects indicates the presence of plasma regions and associated high-energy processes in their surrounding envelopes. This paper numerically simulates and characterises Critical Velocity Ionisation, a potential ionisation process, that can efficiently generate plasma as a result of neutral gas flows interacting with seed magnetized plasmas. By coupling a Gas-MHD interactions code (to simulate the ionisation mechanism) with a substellar global circulation model (to provide the required gas flows) we quantify the spatial extent of the resulting plasma regions, their degree of ionisation and their lifetime for a typical substellar atmosphere. It is found that the typical average ionisation fraction reached at equilibrium (where the ionisation and recombination rates are equal and opposite) ranges from 10-5 to 10-8, at pressures between 10-1 and 10-3 bar, with a trend of increasing ionisation fraction with decreasing atmospheric pressure. The ionisation fractions reached as a result of Critical Velocity Ionisation are sufficient to allow magnetic fields to couple to gas flows in the atmosphere

Bricks for Building the Self Concept of the Disadvantaged Child

Poverty, unemployment, illiteracy, school dropouts, and the necessity for public welfare are not new social problems in our society. At the present time great national effort and much money are being spent to attack many social ills through antipoverty programs. These programs are receiving attention at this time because the increased industrialization and urbanization of today have widened the gap between our American ideals and practices. More people are aware of the resulting inequalities. And people are also aware that society has the power and ability to do something about it. Currently, one of the complex problems facing the United States is putting into practice the ideal of educating all of the children of all of the people.· As a group the children of the poor have not profited from public school education. One effective method of attacking a social problem is through prevention. As a result of this knowledge great emphasis has been placed on improving the schools in the disadvantaged areas