Validation of the communications link analysis and simulation system (CLASS)

CLASS (Communication Link Analysis and Simulation System) is a software package developed for NASA to predict the communication and tracking performance of the Tracking and Data Relay Satellite System (TDRSS) services. The methods used to verify CLASS are described. The usefulness of a software tool such as CLASS depends strongly on the reliability and accuracy of the results it produces. For this reason, considerable attention was paid to validation throughout the CLASS development

The Impact of Short Selling on the Price–Volume Relationship: Evidence from Hong Kong

This paper considers the relationship between traded volume and volatility. We employ short sales data to discriminate between transactions that close existing long positions and transactions that establish new short positions. We test for, and where appropriate, incorporate non–linearity and asymmetry into the modelling process. The evidence supports a non-linear, bi-directional relationship between volume and volatility. The results suggest (i) that the market displays greater volatility following a period of short selling and (ii) that asymmetric responses to positive and negative innovations to returns appear to be exacerbated by short selling.

Comparison of the phase diagram of the half-filled layered organic superconductors with the phase diagram of the RVB theory of the Hubbard-Heisenberg model

We present an resonating valence bond (RVB) theory of superconductivity for the Hubbard--Heisenberg model on an anisotropic triangular lattice. We show that these calculations are consistent with the observed phase diagram of the half-filled layered organic superconductors, such as the beta, beta', kappa and lambda phases of (BEDT-TTF)_2X [bis(ethylenedithio)tetrathiafulvalene] and (BETS)_2X [bis(ethylenedithio)tetraselenafulvalene]. We find a first order transition from a Mott insulator to a d_{x^2-y^2} superconductor with a small superfluid stiffness and a pseudogap with d_{x^2-y^2} symmetry. The Mott--Hubbard transition can be driven either by increasing the on-site Coulomb repulsion, U, or by changing the anisotropy of the two hopping integrals, t'/t. Our results suggest that the ratio t'/t plays an important role in determining the phase diagram of the organic superconductors.Comment: 4 pages, 3 figur

Absence of superconductivity in the half-filled band Hubbard model on the anisotropic triangular lattice

We report exact calculations of magnetic and superconducting pair-pair correlations for the half-filled band Hubbard model on an anisotropic triangular lattice. Our results for the magnetic phases are similar to those obtained with other techniques. The superconducting pair-pair correlations at distances beyond nearest neighbor decrease monotonically with increasing Hubbard interaction U for all anisotropy, indicating the absence of frustration-driven superconductivity within the model.Comment: 4 pages, 4 EPS figure

Addressing Ethical Issues in Studying Men’s Traumatic Stress

Like many human experiences, traumatic stress is highly gendered. Over the past several decades, a sub-stantial number of empirical studies have explored ethical issues in traumatic stress research. However, these studies have typically reported female samples or failed to account for the influence of gender in their analyses of mixed-sex samples. By extension, ethical issues that are relevant to male participants in traumatic stress research are poorly understood. After briefly exploring why the vulnerabilities of male participants are under-explored in traumatic stress research, this article highlights many ethical issues that are important to address when men participate in traumatic stress research, concluding with some sugges-tions for how these might be taken up to advance the field

Deep anthropogenic topsoils in Scotland: a geoarchaeological and historical investigation into distribution, character and conservation under modern land cover

The thesis includes a set of large digital appendices (Appendix 3 and Appendix 4) which are available as a CD on request from the author.Deep anthropogenic topsoils – those augmented through long-term additions of mineral bulk among fertilising agents – retain in both their physical and chemical make-up significant indicators for cultural activity. This project researched the geographical distribution and historical context of deep anthropogenic topsoils in Scotland and the Isles, and used this information to investigate the impact of current land cover upon the cultural information they retain. In so doing, the project investigated the potential for conservation of this significant cultural resource. A review of the historical information available on agricultural and manuring practices for Scotland identified several factors likely to affect deep topsoil distribution and frequency. These were: the availability of bulk manures to Scottish farmers, the significance of the seaweed resource in determining fertiliser strategies in coastal areas, and the influence of urban settlement and associated patterns of domestic and industrial waste disposal on the location of deep topsoils. Evidence for widespread deep topsoil development was limited. The primary data source used – the First Statistical Account of Scotland – was manipulated into a spatial database in ArcView GIS, to which geographical data from the Soil Survey of Scotland and national archaeological survey databases were added. This was used to devise a survey programme aiming both to investigate the potential factors affecting soil development listed above, and to locate deep topsoil sites for analysis. Three sites were identified with deep topsoils under different cover types (woodland, arable and pasture). The urban-influenced context of two of these highlighted the significance of urban settlement to the location of Scottish deep topsoils. Analysis of pH, organic matter, and total phosphorus content showed a correlation between raised organic matter and a corresponding increase in phosphorus content in soils under permanent vegetation. By contrast, soils under arable cultivation showed no such rise. This was attributed to the action of cropping in removing modern organic inputs prior to down-profile cycling. The potential for pasture and woodland cover to affect relict soil signatures was therefore observed. Thin section analysis aimed to both provide micromorphological characterisation of the three deep topsoil sites and investigate the effect of modern land cover on micromorphological indicators. Distinctive differences in micromorphological character were observed between the rural and urban deep topsoils, with the latter showing a strong focus on carbonised fuel residues and industrial wastes. All sites showed a highly individual micromorphological character, reflective of localised fertilising systems. There was no correlation between land cover type and survival of material indictors for anthropogenic activity, with soil cultural indicators surviving well, particularly those characteristic of urban-influenced topsoils. Suggestions for preservation strategies for this potentially rare and highly localised cultural resource included the incorporation of deep anthropogenic topsoil conservation into current government policy relating to care of the rural historic environment, and the improvement of data on the resource through ongoing survey and excavation.This research was funded by Historic Scotland and the University of Stirlin

This is the sky that I see

This is the sky that I see, a Senior Project submitted to The Division of Arts of Bard College, reflects the power we hold in defining and redefining spaces, and how ordinary places can be reimagined for the Othered body. I produced this show to allow the characters to shape and decide their worlds, centering on their relationships and feelings. This is the sky that I see establishes a completely queer world that centers Queer joy and friendship

The Association between Psychotic Symptoms and Romantic Relationship Quality among Young Adult Ethnic Minorites

This study aimed to examine the association between psychotic symptoms and the quality of romantic relationships amongst ethnic minority young adults. Approximately 10.4 million people, which represents 4.2% of the adult population in the U.S, are currently diagnosed with severe mental illnesses, including psychotic disorders. Prior research found that ethnic minorities, in general, have an increased risk of developing psychotic disorders such as schizophrenia. People with SMI generally have issues being and maintaining romantic relationships. However, being in positive romantic relationships is associated with better physical and mental well-being. The final sample size for the study consisted of 411 young adult ethnic minorities. The results showed that while controlling for perceived stress levels, psychotic symptoms were only a significant predictor of romantic relationship quality: relationship satisfaction. Psychotic symptoms did not significantly predict the other relationship quality factors such as relationship trust, relationship commitment, and relationship communication. Study results can direct both future research and clinical practice towards symptom management and incorporating the experience of sexuality and romantic relationships among young adult ethnic minorities with psychosis or SMI