A Spitzer Space Telescope study of SN 2003gd: Still no direct evidence that core-collapse supernovae are major dust factories

We present a new, detailed analysis of late-time mid-infrared observations of the Type II-P supernova (SN) 2003gd. At about 16 months after the explosion, the mid-IR flux is consistent with emission from 4 x 10(-5) M. of newly condensed dust in the ejecta. At 22 months emission from pointlike sources close to the SN position was detected at 8 and 24 mu m. By 42 months the 24 mu m flux had faded. Considerations of luminosity and source size rule out the ejecta of SN 2003gd as the main origin of the emission at 22 months. A possible alternative explanation for the emission at this later epoch is an IR echo from preexisting circumstellar or interstellar dust. We conclude that, contrary to the claim of Sugerman and coworkers, the mid-IR emission from SN 2003gd does not support the presence of 0.02 M. of newly formed dust in the ejecta. There is, as yet, no direct evidence that core-collapse supernovae are major dust factories.

Utility in Willingness to Pay Space: A Tool to Address Confounding Random Scale Effects in Destination Choice to the Alps

We compare two approaches for estimating the distribution of consumers' willingness to pay (WTP) in discrete choice models. The usual procedure is to estimate the distribution of the utility coefficients and then derive the distribution of WTP, which is the ratio of coefficients. The alternative is to estimate the distribution of WTP directly. We apply both approaches to data on site choice in the Alps. We find that the alternative approach fits the data better, reduces the incidence of exceedingly large estimated WTP values, and provides the analyst with greater control in specifying and testing the distribution of WTP. © 2008 Agricultural and Applied Economics Association.

Inverse Gaussian Modeling of Turbulence-Induced Fading in Free-Space Optical Systems

We propose the inverse Gaussian distribution, as a less complex alternative to the classical log-normal model, to describe turbulence-induced fading in free-space optical (FSO) systems operating in weak turbulence conditions and/or in the presence of aperture averaging effects. By conducting goodness of fit tests, we define the range of values of the scintillation index for various multiple-input multiple-output (MIMO) FSO configurations, where the two distributions approximate each other with a certain significance level. Furthermore, the bit error rate performance of two typical MIMO FSO systems is investigated over the new turbulence model; an intensity-modulation/direct detection MIMO FSO system with Q-ary pulse position modulation that employs repetition coding at the transmitter and equal gain combining at the receiver, and a heterodyne MIMO FSO system with differential phase-shift keying and maximal ratio combining at the receiver. Finally, numerical results are presented that validate the theoretical analysis and provide useful insights into the implications of the model parameters on the overall system performance. © 2011 IEEE.

The Disrupted Space: Safety and Security in traditional contexts

One of the core elements of successful planning is the individuals’ experience of their shared open spaces. This paper attributes to the relationship between safety and urban design by means of natural surveillance and security in the city’s shared spaces. It examines how political claims over space reassembled alternative definitions of security in one of Cairo’s oldest quarters, and how ambitious planning schemes were mostly driven by problems of insecurity, chaos and disorder. The main crux to this account is based on original documents, interviews and maps which reveals considerable insights and accounts of how this vision affected the quarter’s spatial quality and the user’s reactions to his new spatial formula. It also reveals conflicting conceptions of safety and security between the planning ambitions and the users experiences, which not only lacked reliable visions for securing the quarter, but also resulted further disruption to their everyday living spaces.

Making space: English women, letter-writing, and the life of the mind, c.1650-1750

This article uses women's letter-writing from the late seventeenth and early eighteenth centuries to explore the home as a site of female intellectual endeavour. Far from representing a static backdrop to the action of domestic life, the home played a dynamic role in women's experiences of the life of the mind and shaped the ways in which women thought and wrote. Letters were penned in dining rooms, parlours and closets, by firesides, and on desks and laps. In their letters, women projected images of themselves scribbling epistles to friends in order to maintain their mental intimacy. Space was both real and imagined and the physical realities of a hand-written and hand-delivered letter gave way to the imaginative possibilities brought by networks of epistolary exchange and the alternative spaces of creative thought. By reinstating the home more fully in the history of female intellectual experience, a more nuanced view of the domestic arena can be developed: one that sees the home not as a site of exclusion and confinement, but as a space for scholarship and exchange. 

An alternative methodology in Schottky diode physics

The fabrication and electrical characterization of Schottky junction diodes have been extensively researched for three-quarters of a century since the original work of Schottky in 1938. This study breaks from the highly standardized regime of such research and provides an alternative methodology that prompts novel, more efficient applications of the adroit Schottky junction in areas such as chemical and thermal sensing. The core departure from standard Schottky diode configuration is that the metal electrode is of comparable or higher resistance than the underlying semiconductor. Further, complete electrical characterization is accomplished through recording four-probe resistance-temperature (R-D-T) characteristics of the device, where electrical sourcing and sensing is done only via the metal electrode and not directly through the semiconductor. Importantly, this results in probing a nominally unbiased junction while eliminating the need for an Ohmic contact to the semiconductor. The characteristic R-D-T plot shows two distinct regions of high (metal) and low (semiconductor) resistances at low and high temperatures, respectively, connected by a crossover region of width, DT, within which there is a large negative temperature coefficient of resistance. The R-D-T characteristic is highly sensitive to the Schottky barrier height; consequently, at a fixed temperature, R-D responds appreciably to small changes in barrier height such as that induced by absorption of a chemical species (e.g., H-2) at the interface. A theoretical model is developed to simulate the R-D-T data and applied to Pd/p-Si and Pt/p-Si Schottky diodes with a range of metal electrode resistance. The analysis gives near-perfect fits to the experimental R-D-T characteristics, yielding the junction properties as fit parameters. The modelling not only helps elucidate the underlying physics but also helps to comprehend the parameter space essential for the discussed applications. Although the primary regime of application is limited to a relatively narrow range (DT) for a given type of diode, the alternative methodology is of universal applicability to all metal-semiconductor combinations forming Schottky contacts. (C) 2015 AIP Publishing LLC.

Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems

Real-space grids are a powerful alternative for the simulation of electronic systems. One of the main advantages of the approach is the flexibility and simplicity of working directly in real space where the different fields are discretized on a grid, combined with competitive numerical performance and great potential for parallelization. These properties constitute a great advantage at the time of implementing and testing new physical models. Based on our experience with the Octopus code, in this article we discuss how the real-space approach has allowed for the recent development of new ideas for the simulation of electronic systems. Among these applications are approaches to calculate response properties, modeling of photoemission, optimal control of quantum systems, simulation of plasmonic systems, and the exact solution of the Schrödinger equation for low-dimensionality systems.

Transportations of space, time and self: The role of therapeutic reading groups in managing mental distress in the community.

Background The practice of reading and discussing literature in groups is long established, stretching back into classical antiquity (Fischer, 2004). While benefits of therapeutic reading groups have been highlighted, research into participants’ perceptions of these groups has been limited (Walwyn & Rowley, 2011). Aims To explore the experiences of those attending therapeutic reading groups, considering the role of both the group, and the literature itself, in participants’ ongoing experiences of distress. Method Eleven participants were recruited from two reading groups in the South East of England. One focus group was run, and eight individuals self selected for individual interviews. The data were analysed together using a thematic analysis drawing on dialogical theories. Results Participants described the group as an anchor, which enabled them to use fiction to facilitate the discussion of difficult emotional topics, without referring directly to personal experience. Two aspects of this process are explored in detail: the use of narratives as transportation, helping to mitigate the intensity of distress; and using fiction to explore possibilities, alternative selves and lives. Conclusions For those who are interested and able, reading groups offer a relatively de-stigmatised route to exploring and mediating experiences of distress. Implications in the present UK funding environment are discussed.

Loss Modelling of Three-Level Inverters controlled with Space Vector Modulation Technique

The objective of this master’s thesis is to investigate the loss behavior of three-level ANPC inverter and compare it with conventional NPC inverter. The both inverters are controlled with mature space vector modulation strategy. In order to provide the comparison both accurate and detailed enough NPC and ANPC simulation models should be obtained. The similar control model of SVM is utilized for both NPC and ANPC inverter models. The principles of control algorithms, the structure and description of models are clarified. The power loss calculation model is based on practical calculation approaches with certain assumptions. The comparison between NPC and ANPC topologies is presented based on results obtained for each semiconductor device, their switching and conduction losses and efficiency of the inverters. Alternative switching states of ANPC topology allow distributing losses among the switches more evenly, than in NPC inverter. Obviously, the losses of a switching device depend on its position in the topology. Losses distribution among the components in ANPC topology allows reducing the stress on certain switches, thus losses are equally distributed among the semiconductors, however the efficiency of the inverters is the same. As a new contribution to earlier studies, the obtained models of SVM control, NPC and ANPC inverters have been built. Thus, this thesis can be used in further more complicated modelling of full-power converters for modern multi-megawatt wind energy conversion systems.

Steeltown scene : genre, performance and identity in the alternative independent music scene in Hamilton, Ontario

This thesis examines the independent alternative music scene in the city of Hamilton, Ontario, also known, with reference to its industrial heritage, as "Steeltown." Drawing on the growing literature on the relationship between place and popular music, on my own experience as a local musician, direct observation of performances and of venues and other sites of interaction, as well as ethnographic interviews with scene participants, I focus on the role of space, genre and performance within the scene, and their contribution to a sense of local identity. In particular, I argue that the live performance event is essential to the success of the local music scene, as it represents an immediate process, a connection between performers and audience, one which is temporally rooted in the present. My research suggests that the Hamilton alternative music scene has become postmodern, embracing forms of "indie" music that lie outside of mainstream taste, and particularly those which engage in the exploration and deconstruction of pre-existing genres. Eventually, however, the creative successes of an "indiescene" permeate mass culture and often become co-opted into the popular music mainstream, a process which, in turn, promotes new experimentation and innovation at the local level.

The Transformation Problem : an Aleternative Solution with an Identical Aggregate Profit Rate in the Labor value and the Monetary Space.

The aim of this paper is to demonstrate that, even if Marx's solution to the transformation problem can be modified, his basic conclusions remain valid. the proposed alternative solution which is presented hare is based on the constraint of a common general profit rate in both spaces and a money wage level which will be determined simultaneously with prices.

The Transformation Problem : an Aleternative Solution with an Identical Aggregate Profit Rate in the Labor value and the Monetary Space.

The aim of this paper is to demonstrate that, even if Marx's solution to the transformation problem can be modified, his basic conclusions remain valid. the proposed alternative solution which is presented hare is based on the constraint of a common general profit rate in both spaces and a money wage level which will be determined simultaneously with prices.

Estimating surface CO2 fluxes from space-borne dry air mole fraction observations using an Ensemble Kalman filter

We have developed an ensemble Kalman Filter (EnKF) to estimate 8-day regional surface fluxes of CO2 from space-borne CO2 dry-air mole fraction observations (XCO2) and evaluate the approach using a series of synthetic experiments, in preparation for data from the NASA Orbiting Carbon Observatory (OCO). The 32-day duty cycle of OCO alternates every 16 days between nadir and glint measurements of backscattered solar radiation at short-wave infrared wavelengths. The EnKF uses an ensemble of states to represent the error covariances to estimate 8-day CO2 surface fluxes over 144 geographical regions. We use a 12×8-day lag window, recognising that XCO2 measurements include surface flux information from prior time windows. The observation operator that relates surface CO2 fluxes to atmospheric distributions of XCO2 includes: a) the GEOS-Chem transport model that relates surface fluxes to global 3-D distributions of CO2 concentrations, which are sampled at the time and location of OCO measurements that are cloud-free and have aerosol optical depths <0.3; and b) scene-dependent averaging kernels that relate the CO2 profiles to XCO2, accounting for differences between nadir and glint measurements, and the associated scene-dependent observation errors. We show that OCO XCO2 measurements significantly reduce the uncertainties of surface CO2 flux estimates. Glint measurements are generally better at constraining ocean CO2 flux estimates. Nadir XCO2 measurements over the terrestrial tropics are sparse throughout the year because of either clouds or smoke. Glint measurements provide the most effective constraint for estimating tropical terrestrial CO2 fluxes by accurately sampling fresh continental outflow over neighbouring oceans. We also present results from sensitivity experiments that investigate how flux estimates change with 1) bias and unbiased errors, 2) alternative duty cycles, 3) measurement density and correlations, 4) the spatial resolution of estimated flux estimates, and 5) reducing the length of the lag window and the size of the ensemble. At the revision stage of this manuscript, the OCO instrument failed to reach its orbit after it was launched on 24 February 2009. The EnKF formulation presented here is also applicable to GOSAT measurements of CO2 and CH4.

Evolving features-algorithms knowledge map to support NIDS data intelligence and learning loop architecting – a generalised approach to NIDS pattern feature space knowledge processing

This paper describes a proposed new approach to the Computer Network Security Intrusion Detection Systems (NIDS) application domain knowledge processing focused on a topic map technology-enabled representation of features of the threat pattern space as well as the knowledge of situated efficacy of alternative candidate algorithms for pattern recognition within the NIDS domain. Thus an integrative knowledge representation framework for virtualisation, data intelligence and learning loop architecting in the NIDS domain is described together with specific aspects of its deployment.