Electron and Photon Interactions in the Regime of Strong LPM Suppression

Most searches for ultra-high energy (UHE) astrophysical neutrinos look for radio emission from the electromagnetic and hadronic showers produced in their interactions. The radio frequency spectrum and angular distribution depend on the shower development, so are sensitive to the interaction cross sections. At energies above about 10^{16} eV (in ice), the Landau-Pomeranchuk-Migdal (LPM) effect significantly reduces the cross sections for the two dominant electromagnetic interactions: bremsstrahlung and pair production. At higher energies, above about 10^{20} eV, the photonuclear cross section becomes larger than that for pair production, and direct pair production and electronuclear interactions become dominant over bremsstrahlung. The electron interaction length reaches a maximum around 10^{21} eV, and then decreases slowly as the electron energy increases further. In this regime, the growth in the photon cross section and electron energy loss moderates the rise in nu_e shower length, which rises from ~10 m at 10^{16} eV to ~50 m at 10^{19} eV and ~100 m at 10^{20} eV, but only to ~1 km at 10^{24} eV. In contrast, without photonuclear and electronuclear interactions, the shower length would be over 10 km at 10^{24} eV.Comment: 10 pages, 9 figures. Submitted to Physical Review

Starting Out Right: A Cluster Evaluation of the Early Childhood Grants of the John S. and James L. Knight Foundation: Year 3 Final Report

Evaluates Knight's early childhood grantmaking in twelve communities, with a focus on grants that transform systems and build networks at a scale sufficient to create meaningful change. Presents grantee results and lessons learned

Developing Higher Consciousness: The Effects of Mantra Meditation on the Development of Self-Actualizing Qualities in Teachers

This qualitative study focuses on teachers ranging from the elementary to secondary level who have practiced mantra meditation for at least three years while also teaching. By utilizing the methodology of portraiture, this study endeavored to determine if the practice of mantra meditation creates self-actualizing qualities in teachers, how teachers who practice mantra meditation perceive their response to stress and conflict in the classroom, and how teachers who practice mantra meditation perceive the effects of meditation on their personal and professional lives. The methodology of portraiture was chosen because according to Lawrence-Lightfoot, with its focus on narrative, with its use of metaphor and symbol, portraiture intends to address wider, more eclectic audiences. The attempt is to move beyond academy\u27s inner circle, to speak in a language that is not coded or exclusive… (Lawrence-Lightfoot and Davis, 1997, p. 10). Through personal narratives composed by the three participants and interviews conducted by the researcher, data was collected and analyzed. The findings indicate that each participant perceived the practice of mantra meditation as positively contributing to his/her personal and professional lives, enabled him/her to feel psychologically healthier and better equipped to handle the stress and conflict encountered within the classroom, and created a sense of interactions with students being more positive and rewarding. Each of the three participants also displayed certain dispositions, and demonstrated through their narratives and their interviews, that they embody certain qualities of self-actualization

Creating Virtual Experiences in Computer-Mediated Environments

Although much excitement has arisen over the potential for "interactivity" on the Web, very little is understood about what exactly creates a sense of interactivity and what impact it has on user behavior. Businesses are spending millions of dollars to add interactivity to their Web sites, in the form of games, animated pictures, and personalization tools, without knowing exactly what impact this has on their customers. In this research, the critical components of this computer-mediated interactivity and, more broadly, the larger realm of virtual experiences that it can create are explored. In doing so, I investigate the impact of the new media capabilities on consumers' interpretations of these experiences and the product-based persuasion that results from them. Given that direct product experience is usually the optimal method for consumers to learn about product information (Berger and Mitchell 1989; Marks and Kamins 1988; Smith and Swinyard 1988; Wu and Shaffer 1987), one of a marketer's goals should be to strive for verisimilitude in any indirect communications. This research explores how the Web might emulate direct experience and how the effects of these virtual experiences might differ from those resulting from exposure to traditional advertising media. In order to measure the sense of experience within a computer-mediated environment, I employ the construct of telepresence. Telepresence is defined as a sense of presence in a mediated environment, wherein the user experiences the computer-mediated environment as less mediated than it actually is (Steuer 1992). This construct of telepresence is also used to evaluate the process by which media characteristics influence consumer responses to marketing communications. The two primary objectives of this research are to understand how telepresence is created and how it affects consumer response to computer-mediated communications. I explore two critical media characteristics that are hypothesized to influence telepresence: (1) user control and (2) media richness. The potential for user control is a critical element of interactivity (Lombard and Snyder-Duch 2001). In addition, on the Web, it is controllable by the marketer Web (Ariely 2000). Media richness represents the sensory breadth (number of communication channels) and depth (quality within each channel) of the stimuli (Steuer 1992). As the degree of telepresence increases, the more similar the mediated experience will be to an actual direct product experience. Thus, when a state of telepresence is created in a persuasive communication, marketers may expect consumers to develop more intense attitudes and beliefs toward the product and its attributes than they would in a more mediated communication experience, such as that typically engendered by television or print advertisements (Fazio and Zanna 1981). Two experiments are conducted using a 2 (media richness) X 2 (user control) design in a computer-mediated environment (Figure 1). Wine (Study 1) and face cream (Study 2) are used because of the importance of experience attributes in product selection and preference formation for these two categories. Control is operationalized as control over the form of the information -- the order of information acquisition, holding the information content constant. "High user control" participants had control over the order in which they viewed the categories. These participants could view the categories in any order they desired, but were required to see all before exiting. The subjects in the "low user control" condition were guided through the topics in a pre-determined order. Media richness was operationalized via the modality of the medium. That is, media breadth was manipulated, while holding depth constant. In the low media richness condition participants were exposed to text and still pictures, with no sound. In the high media richness condition, full-motion video and sound were added. Both stimuli were pre-tested to to assure information equivalence. Telepresence is measured with a variation of the 7-item scale employed by Kim and Biocca (1997) and Novak et al. (2000). Attribute belief strength and product attitude intensity measures are also collected. The results show that both user control and media richness had significant positive influences on the creation of telepresence and on product attribute beliefs and overall attitudes toward the product. In Study 2, we also find a significant positive interaction effect between user control and media richness in the creation of telepresence. In both studies, telepresence was found to have a significant and positive impact on persuasion at both the attribute and product levels. Moreover, the results reveal the process by which this occurs; telepresence is shown to serve as a mediating variable in the relationship between these two media characteristics, represented through a "realism index," and attribute and product-level persuasion. Finally, I test two variations of the 7-item telepresence scale; comparisons of the results with those from previous studies provide further evidence of the unidimensionality of this scale and offer suggestions for future scale refinements. This study answers a number of key questions about consumer response to advertising in computer-mediated environments. This research has demonstrated a novel way of operationalizing control and media richness in a computer-mediated environment, and of measuring the role of telepresence in the process. A systematic program of research exploring the impact of the many facets of control and combinations of modalities on different types of individuals is necessary before we can be confident in our understanding of the impact of computer-mediated product experiences on consumer behavior.Internet, interactivity, consumer behavior, telepresence, media, advertising,

Promoting Effective Early Learning: What Every Policymaker and Educator Should Know

This brief provides a blueprint for state and local policymakers, early learning administrators, teachers, families, community leaders, and researchers to use effective preschool curricula and teaching strategies to help low-income young children close the achievement gap in early literacy and math to be ready for kindergarten like their more affluent peers. It is part of a series of publications from the Pathways to Early School Success project of NCCP that addresses the question: "What will it take to ensure that young low-income children succeed in the early school years?" The brief and the more in-depth report—Effective Preschool Curricula and Teaching Strategies—are both based on a meeting that NCCP convened bringing together distinguished researchers, as well as a careful review of recently funded research. Other issue briefs in the Pathways project have focused on the importance of strategies to promote social and emotional competence in infants, toddlers and preschoolers: Helping the Most Vulnerable Infants, Toddlers, and Their Families, and Resources to Promote Social and Emotional Health and School Readiness in Young Children and Families—A Community Guid