Distributed resource discovery using a context sensitive infrastructure

Distributed Resource Discovery in a World Wide Web environment using full-text indices will never scale. The distinct properties of WWW information (volume, rate of change, topical diversity) limits the scaleability of traditional approaches to distributed Resource Discovery. An approach combining metadata clustering and query routing can, on the other hand, be proven to scale much better. This paper presents the Content-Sensitive Infrastructure, which is a design building on these results. We also present an analytical framework for comparing scaleability of different distribution strategies

A high energy electron-photon detector employing flash tube arrays

The development of a high energy electromagnetic shower detector for use in high energy electron or photon detection, particularly in machine experiments, is described. The detector is a modified version of a prototype chamber, which was successfully tested, and which is described briefly in this thesis. The detector gives fully digitised information from which incident particle energies and trajectories can be estimated. The detector consists of twelve flash tube arrays sandwiched between lead target. A total of 768 tubes are employed. They have an internal diameter of 0.8 cm a wall thickness of 0.03 cm. and are filled with a gas mixture of Ne (70%) –He (30%) 2% CH (_4) at 2.3 atmospheres pressure. The operation of these tubes under various working conditions has been extensively studied and the results are presented in the thesis. The detector has been tested in the positron beam at the Daresbury Laboratory, where digitised information was obtained using a computerised data acquisition system. The energies of the positrons used ranged from 0.1 to 3.5 GeV. Analysis of the data showed that the chamber operated satisfactorily in high backgrounds of radiation and was very capable in the detection of electromagnetic showers, giving energy and spatial resolutions comparable to those obtained by the conventional, more complex and more expensive detecting systems. However, the use of the detector was restricted to working at several events per minute, due to the build up of large induced clearing fields inside the flash tubes

Simplified Models for Dark Matter Interacting with Quarks

We investigate simplified models in which dark matter particles, taken to be either Dirac or Majorana fermions, couple to quarks via colored mediators. We determine bounds from colliders and direct detection experiments, and show how the interplay of the two leads to a complementary view of this class of dark matter models. Forecasts for future searches in light of the current constraints are presented.Comment: 12 pages, 13 figures (39 images) Fixed erroneous calculation and updated plot

Interpreting Dark Matter Direct Detection Independently of the Local Velocity and Density Distribution

We demonstrate precisely what particle physics information can be extracted from a single direct detection observation of dark matter while making absolutely no assumptions about the local velocity distribution and local density of dark matter. Our central conclusions follow from a very simple observation: the velocity distribution of dark matter is positive definite, f(v) >= 0. We demonstrate the utility of this result in several ways. First, we show a falling deconvoluted recoil spectrum (deconvoluted of the nuclear form factor), such as from ordinary elastic scattering, can be "mocked up" by any mass of dark matter above a kinematic minimum. As an example, we show that dark matter much heavier than previously considered can explain the CoGeNT excess. Specifically, m_chi < m_Ge} can be in just as good agreement as light dark matter, while m_\chi > m_Ge depends on understanding the sensitivity of Xenon to dark matter at very low recoil energies, E_R ~ 6 keVnr. Second, we show that any rise in the deconvoluted recoil spectrum represents distinct particle physics information that cannot be faked by an arbitrary f(v). As examples of resulting non-trivial particle physics, we show that inelastic dark matter and dark matter with a form factor can both yield such a rise

PTEN, Longevity and Age-related Diseases

Since the discovery of PTEN, this protein has been shown to be an effective suppressor of cancer and a contributor to longevity. This report will review, in depth, the associations between PTEN and other molecules, its mutations and regulations in order to present how PTEN can be used to increase longevity. This report will collect recent research of PTEN and use this to discuss PTEN’s role in caloric restriction, antioxidative defense of DNA-damage and the role it plays in suppressing tumors. The report will also discuss that variety of ways that PTEN can be compromised, through mutations, complete loss of alleles and its main antagonist, the PI3K/AKT pathway

Self-harm, substance use and psychological distress in the Australian general population

AIMS: To examine predictors of self-harm, especially substance use and psychological distress, in an Australian adult general population sample. DESIGN: Sequential-cohort design with follow-up every four years. SETTING: Australian general population. PARTICIPANTS: A random sample of adults aged 20-24 and 40-44 years (at baseline) living in and around the Australian Capital Territory. MEASUREMENTS: Self-report survey including items on four common forms of self-harm. Psychological distress was indexed by the combined Goldberg Anxiety and Depression scale scores and alcohol problems by the Alcohol Use Disorders Identification Test (AUDIT). FINDINGS: 4,160 people (84% of baseline) were re-interviewed at eight years: 4126 reported their self-harm status. Past year self-harm was reported by 8.2% (95% CI 7.4-9.0%) of participants (males: 9.3% (8.0-10.6%), females: 7.3% (6.2-8.4%)). Several forms of substance use – smoking (odds ratio = 1.52), marijuana use (odds ratio = 1.77), and drinking alcohol at a level likely to cause dependence (AUDIT score > 20) (odds ratio = 2.08) – were independently predictive of past year self-harm. Additional key risk factors for self-harm in the past year were childhood sexual abuse by a parent (odds ratio = 3.07), bisexual orientation (odds ratio = 2.65), younger age (odds ratio = 2.23) and male gender (odds ratio = 1.86). Other independent predictors were years of education, adverse life events, psychological distress and financial strain. CONCLUSIONS: Self-harm in young and middle-aged adults appears to be associated with current smoking, marijuana and “dependent†alcohol use. Other independent predictors include younger age, male gender, bisexual orientation, financial strain, education level, psychological distress, adverse life events and sexual abuse by a parent

Elucidating the structural composition of a Fe-N-C catalyst by nuclear and electron resonance techniques

Fe–N–C catalysts are very promising materials for fuel cells and metal–air batteries. This work gives fundamental insights into the structural composition of an Fe–N–C catalyst and highlights the importance of an in‐depth characterization. By nuclear‐ and electron‐resonance techniques, we are able to show that even after mild pyrolysis and acid leaching, the catalyst contains considerable fractions of α‐iron and, surprisingly, iron oxide. Our work makes it questionable to what extent FeN4 sites can be present in Fe–N–C catalysts prepared by pyrolysis at 900 °C and above. The simulation of the iron partial density of phonon states enables the identification of three FeN4 species in our catalyst, one of them comprising a sixfold coordination with end‐on bonded oxygen as one of the axial ligands

On the generalized continuity equation

A generalized continuity equation extending the ordinary continuity equation has been found using quanternions. It is shown to be compatible with Dirac, Schrodinger, Klein-Gordon and diffusion equations. This generalized equation is Lorentz invariant. The transport properties of electrons are found to be governed by Schrodinger-like equation and not by the diffusion equation.Comment: 9 Latex pages, no figure

Autocatalytic plume pinch-off

A localized source of buoyancy flux in a non-reactive fluid medium creates a plume. The flux can be provided by either heat, a compositional difference between the fluid comprising the plume and its surroundings, or a combination of both. For autocatalytic plumes produced by the iodate-arsenous acid reaction, however, buoyancy is produced along the entire reacting interface between the plume and its surroundings. Buoyancy production at the moving interface drives fluid motion, which in turn generates flow that advects the reaction front. As a consequence of this interplay between fluid flow and chemical reaction, autocatalytic plumes exhibit a rich dynamics during their ascent through the reactant medium. One of the more interesting dynamical features is the production of an accelerating vortical plume head that in certain cases pinches-off and detaches from the upwelling conduit. After pinch-off, a new plume head forms in the conduit below, and this can lead to multiple generations of plume heads for a single plume initiation. We investigated the pinch-off process using both experimentation and simulation. Experiments were performed using various concentrations of glycerol, in which it was found that repeated pinch-off occurs exclusively in a specific concentration range. Autocatalytic plume simulations revealed that pinch-off is triggered by the appearance of accelerating flow in the plume conduit.Comment: 10 figures. Accepted for publication in Phys Rev E. See also http://www.physics.utoronto.ca/nonlinear/papers_chemwave.htm

Strain Measurements of Chondrules and Refraction Inclusion in Allende

This study uses traditional strain measurement techniques, combined with X-ray computerized tomography (CT), to evaluate petrographic evidence in the Allende CV3 chondrite for preferred orientation and to measure strain in three dimensions. The existence of petrofabrics and lineations was first observed in carbonaceous meteorites in the 1960's. Yet, fifty years later only a few studies have reported that meteorites record such features. Impacts are often cited as the mechanism for this feature, although plastic deformation from overburden and nebular imbrication have also been proposed. Previous work conducted on the Leoville CV3 and the Parnallee LL3 chondrites, exhibited a minimum uniaxial shortening of 33% and 21%, respectively. Petrofabrics in Allende CV3 have been looked at before; previous workers using Electron Back Scatter Diffraction (EBSD) found a major-axis alignment of olivine inside dark inclusions and an "augen"-like preferred orientation of olivine grains around more competent chondrule