Mechanical properties of brittle materials

Brittle materials are difficult to tensile test because of gripping problems. They either crack in conventional grips or they are crushed. Furthermore, they may be difficult to make into tensile specimens having, for example, threated ends or donut shapes. To overcome the problem, simple rectangular shapes can be used in bending (i.e., a simple beam) in order to obtain the modulus of rupture and the elastic modulus. The equipment necessary consists of a fixture for supporting the specimens horizontally at two points, these points contact points being rollers which are free to rotate. The force necessary to bend the specimen is produced by a tup attached to the crosshead of an Instron machine. Here, the experimental procedure is explained

qq-graded Heisenberg algebras and deformed supersymmetries

The notion of $q$-grading on the enveloping algebra generated by products of q-deformed Heisenberg algebras is introduced for $q$ complex number in the unit disc. Within this formulation, we consider the extension of the notion of supersymmetry in the enveloping algebra. We recover the ordinary $\mathbb{Z}_2$ grading or Grassmann parity for associative superalgebra, and a modified version of the usual supersymmetry. As a specific problem, we focus on the interesting limit $q\to -1$ for which the Arik and Coon deformation of the Heisenberg algebra allows to map fermionic modes to bosonic ones in a modified sense. Different algebraic consequences are discussed.Comment: 2 figure

Station-Keeping Requirements for Constellations of Free-Flying Collectors Used for Astronomical Imaging in Space

The accuracy requirements on station-keeping for constellations of free-flying collectors coupled as (future) imaging arrays in space for astrophysics applications are examined. The basic imaging element of these arrays is the two-element interferometer. Accurate knowledge of two quantities is required: the \textit{projected baseline length}, which is the distance between the two interferometer elements projected on the plane tranverse to the line of sight to the target; and the \textit{optical path difference}, which is the difference in the distances from that transverse plane to the beam combiner. ``Rules-of-thumb'' are determined for the typical accuracy required on these parameters. The requirement on the projected baseline length is a \textit{knowledge} requirement and depends on the angular size of the targets of interest; it is generally at a level of half a meter for typical stellar targets, decreasing to perhaps a few centimeters only for the widest attainable fields of view. The requirement on the optical path difference is a \textit{control} requirement and is much tighter, depending on the bandwidth of the signal; it is at a level of half a wavelength for narrow (few %) signal bands, decreasing to $\approx 0.2 \lambda$ for the broadest bandwidths expected to be useful. Translation of these requirements into engineering requirements on station-keeping accuracy depends on the specific details of the collector constellation geometry. Several examples are provided to guide future application of the criteria presented here. Some implications for the design of such collector constellations and for the methods used to transform the information acquired into images are discussed.Comment: 13 pages, 6 figures, accepted 6/29/07 for the August 2007 issue of PAS

Examination of Affective Responses to Images in Sponsorship-Linked Marketing

Sponsorship of sports, arts, charity and entertainment events are all viewed as capable in building corporate and brand image. In this process, visual images are a key vehicle in the transportation of affect from an event to a brand. While the overall positive feeling of a sponsored event or activity is argued to rub-off on a brand, we know less about how individual images function in this process and we know even less about the role of negative images. Here, three experiments consider the potential of affect transfer from images to brands. All three experiments show explicit transfer of affect, and one finds implicit evaluative change. Importantly, positive images when mixed with negative are off-setting. This research suggests that when negative events occur and are captured and repeated in the media, practitioners able to supply positive images may be able to control negative affective responses to some degree

Stigma resistance at the personal, peer, and public levels: A new conceptual model.

Stigma resistance is consistently linked with key recovery outcomes, yet theoretical work is limited. This study explored stigma resistance from the perspective of individuals with serious mental illness (SMI). Twenty-four individuals with SMI who were either peer-service providers (those with lived experience providing services; N = 14) or consumers of mental health services (N = 10) engaged in semistructured interviews regarding experiences with stigma, self-stigma, and stigma resistance, including key elements of this process and examples of situations in which they resisted stigma. Stigma resistance is an ongoing, active process that involves using one’s experiences, knowledge, and sets of skills at the (1) personal, (2) peer, and (3) public levels. Stigma resistance at the personal level involves (a) not believing stigma or catching and challenging stigmatizing thoughts, (b) empowering oneself by learning about mental health and recovery, (c) maintaining one’s recovery and proving stigma wrong, and (d) developing a meaningful identity apart from mental illness. Stigma resistance at the peer level involves using one’s experiences to help others fight stigma and at the public level, resistance involved (a) education, (b) challenging stigma, (c) disclosing one’s lived experience, and (d) advocacy work. Findings present a more nuanced conceptualization of resisting stigma, grounded in the experiences of people with SMI. Stigma resistance is an ongoing, active process of using one’s experiences, skills, and knowledge to develop a positive identity. Interventions should consider focusing on personal stigma resistance early on and increasing the incorporation of peers into services

One-loop effective potential for SO(10) GUT theories in de Sitter space

Zeta-function regularization is applied to evaluate the one-loop effective potential for SO(10) grand-unified theories in de Sitter cosmologies. When the Higgs scalar field belongs to the 210-dimensional irreducible representation of SO(10), attention is focused on the mass matrix relevant for the SU(3)xSU(2)xU(1) symmetry-breaking direction, to agree with low-energy phenomenology of the particle-physics standard model. The analysis is restricted to those values of the tree-level-potential parameters for which the absolute minima of the classical potential have been evaluated. As shown in the recent literature, such minima turn out to be SO(6)xSO(4)- or SU(3)xSU(2)xSU(2)xU(1)-invariant. Electroweak phenomenology is more naturally derived, however, from the former minima. Hence the values of the parameters leading to the alternative set of minima have been discarded. Within this framework, flat-space limit and general form of the one-loop effective potential are studied in detail by using analytic and numerical methods. It turns out that, as far as the absolute-minimum direction is concerned, the flat-space limit of the one-loop calculation about a de Sitter background does not change the results previously obtained in the literature, where the tree-level potential in flat space-time was studied. Moreover, when curvature effects are no longer negligible in the one-loop potential, it is found that the early universe remains bound to reach only the SO(6)xSO(4) absolute minimum.Comment: 25 pages, plain Tex, plus Latex file of the tables appended at the end. Published in Classical and Quantum Gravity, Vol. 11, pp. 2031-2044, August 199

Romantic Partnerships and the Dispersion of Social Ties: A Network Analysis of Relationship Status on Facebook

A crucial task in the analysis of on-line social-networking systems is to identify important people --- those linked by strong social ties --- within an individual's network neighborhood. Here we investigate this question for a particular category of strong ties, those involving spouses or romantic partners. We organize our analysis around a basic question: given all the connections among a person's friends, can you recognize his or her romantic partner from the network structure alone? Using data from a large sample of Facebook users, we find that this task can be accomplished with high accuracy, but doing so requires the development of a new measure of tie strength that we term `dispersion' --- the extent to which two people's mutual friends are not themselves well-connected. The results offer methods for identifying types of structurally significant people in on-line applications, and suggest a potential expansion of existing theories of tie strength.Comment: Proc. 17th ACM Conference on Computer Supported Cooperative Work and Social Computing (CSCW), 201

The College of Wooster Inauguration Address: Independent Minds, Working Together

The inaugural address of President Grant H. Cornwell.https://openworks.wooster.edu/presidents/1044/thumbnail.jp