Subspace design of low-rank estimators for higher-order statistics

Higher-order statistics (HOS) are well known for their robustness to additive Gaussian noise and ability to preserve phase. HOS estimates, on the other hand, have been criticized for high complexity and the need for long data in order to maintain small variance. Since rank reduction offers a general principle for reduction of estimator variance and complexity, we consider the problem of designing low-rank estimators for HOS. We propose three methods for choosing the transformation matrix that reduces the mean-square error (MSE) associated with the low-rank HOS estimates. We also demonstrate the advantages of using low-rank third-order moment estimates for blind system estimation. Results indicate that the full rank MSE corresponding to some data length N can be attained by a low-rank estimator corresponding to a length significantly smaller than N.     

Heroes of resiliency and reciprocity: teachers’ supporting role for reconceptualizing superhero play in early childhood settings

Superhero play is a specialised form of fantasy play with considerable appeal to young children. During superhero play, children have opportunities to pretend and often to play different types of roles within a safe and caring environment. When guided appropriately in an early childhood classroom, superhero play gives young children opportunities to gain a sense of mastery and empowerment as well as developmentally appropriate benefits by improving language skills, problem-solving and cooperation with peers. By recognising and modelling the characteristics of resiliency and promoting kindness with peers during superhero play, teachers can encourage children to be kind and resilient heroes to classroom friends. As today’s classrooms increasingly include diverse members, it is important for young children to understand and appreciate the peers they play and learn with at school. The result may be a richer learning experience and may break down barriers that can produce unfairness, bullying and aggressive behaviours. This article explores the essence of superhero fantasy play along with its benefits for young children. In addition, the article examines the challenge of superhero play in classrooms for early childhood educators by exploring teachers’ roles in play. A new pedagogy for supporting superhero play is introduced, addressing spiritual and educational concerns by suggesting ways in which teachers can increase resiliency, encourage new friendships and build classroom community among peers during play and classroom activities.     

FIRST YEAR IMPLEMENTATION OF A PROJECT-BASED LEARNING APPROACH: THE NEED FOR ADDRESSING TEACHERS�� ORIENTATIONS IN THE ERA OF REFORM

The purpose of this study was to examine the extent to which three teachers’ professional experience and existing orientations toward teaching and learning mathematics and science influenced their implementation of a project-based curriculum (i.e. project-based learning (PBL)). Data sources included interviews, videotapes of classroom activity, and a teaching philosophy questionnaire. Data analysis was conducted using an iterative coding technique. We found coherency between the teachers’ perceived orientations and their emergent ideas about PBL, their sense of PBL as being compatible with their goals, and the specific challenges with which they struggled. All the teachers wanted their students to be successful; however, different definitions of success led to quite different approaches toward teaching, and for the most part, these differences appeared to have occurred because of existing orientations the teachers held for teaching their discipline. Implications for professional development taking into account teachers’ orientations and thus their professional experience are discussed, as well as disciplinary challenges to using PBL.     

African American college students excelling in the sciences: College and postcollege outcomes in the Meyerhoff Scholars Program

This paper describes and assesses the effectiveness of the Meyerhoff Scholars Program at the University of Maryland, Baltimore County (UMBC). The Program is designed to increase the number of underrepresented minorities who pursue graduate and professional degrees in science and engineering. Until 1996 the program admitted African American students exclusively, and the current study focuses only on students from that group. The Meyerhoff students have achieved higher grade point averages, graduated in science and engineering at higher rates, and gained admittance to graduate schools at higher rates than multiple current and historical comparison samples. Student survey and interview data revealed that a number of program components were viewed as being especially important contributors to students' academic success: Program Community, Study Groups, Summer Bridge Program, Financial Support, Program Staff, and Research Internships and Mentors. © 2000 John Wiley & Sons, Inc. J Res Sci Teach 37: 629–654, 2000     

“Unskilled Laborers”

Advancement of knowledge and progress in technology drives the need for protecting inventions, new ideas, writings, music, and other media. While abundant, intellectual property and copyright issues are not simple, and the United States has adopted multiple rules via treaties worldwide. Academia has been fortunate with regard to the freedom provided by the fair use doctrine. Despite the freedoms, however, some feel that liberty is now limited by the Digital Millennium Copyright Act of 1998 (DMCA) and other rules being placed on intellectual property use (Carlson 2004).     

CORRECTIONAL POST‐SECONDARY EDUCATION: THE EXPANDING ROLE OF COMMUNITY COLLEGES

More than 75 percent of post‐secondary institutions offering education programs in prisons are community and vocational/ technical colleges. The predominance of community colleges among correctional education providers is a major change from the early 1970's when two‐thirds of such programs were provided by four‐year institutions.

Over 260 community colleges provide programs and services to the 26,000 inmates participating in higher education. Results of a survey on correctional post‐secondary education indicate that these programs are in many ways different from those educational institutions provide on their own campuses. For example, they generally, have different admission standards, are administered by part‐time staff, and rely upon part‐time and adjunct faculty.

Community and junior college administrators are urged to closely examine the operation and quality of their correctional programs and the need for evaluative research on the long‐term effects of these programs is also stressed.     

Action research: A situated perspective

Rigoberta Menchú has become an icon for the struggles of oppressed peoples for justice and self-determination. For many academics and activists around the world, the accusations of lying made against Ms. Menchú by David Stoll brought into sharp focus the politics of "truthmaking" and the absolutist categories of fact and fiction. In this attempt to discredit Ms. Menchú, and through her, the Mayan experience of genocide by the Guatemalan military and its U.S. sponsors, important questions have been raised about how and when Third World women can speak, the conditions under which they will be heard, and the strategies used to silence them. In this paper, the author draws upon some of the lessons of the Rigoberta Menchú case to examine the politics of truth making in Canada in a recent controversy regarding a speech she made criticizing American foreign policy and urging the women's movement to mobilize against America's War on Terrorism. The highly personalized nature of the attacks on the author by political and media elites sought to accomplish a closing down of public space for informed debate about the realities of U.S. foreign policy and to silence dissent. Repeatedly emphasizing her status as an immigrant outsider, this controversy also contributed to the (ongoing) racialization of people of color as a treacherous "enemy" within the nation's geographical borders, against whom "Canadians" had to be mobilized.     

Constraints Affecting ICT Utilization by Agricultural Extension Officers in the Niger Delta,Nigeria

Abstract

The study focused on constraints affecting the utilization of Information and Communication Technologies (ICT) for agricultural extension activities by Agricultural Extension Officers in Nigeria's Niger Delta Region. Data were derived from 160 extension officers affiliated to both public and private extension organizations in four states of the Niger Delta. Findings revealed important specific constraints to include: poor ICT infrastructure development, high cost of broadcast equipment, high charges for radio/television presentations, high cost of access/interconnectivity and electricity power problems. The use of Factor Analysis aided to crystallize identified constraints into three factors of ‘poor enabling environment’, ‘lack of access’ and ‘dissemination of unrelated information’. Against the background of several national government initiatives to develop the infrastructure base of the country, recommendations are proffered to ameliorate ICT use constraints.     

Determinants of withdrawal behavior: An exploratory study

Research on college persistence has typically classified nonreturnees as dropouts. Recently, this practice has been criticized by Tinto (1987) who argues that such a practice merges together different types of withdrawal behavior whose determinants may vary as a function of the particular departure behavior under consideration. This paper empirically examines whether the determinants of decisions to withdraw from the institution are similar to those affecting decisions to transfer to other institutions of higher education for the 1984 entering freshman class at a large southern institution. Results provide support for Tinto's proposition of differentiating between different types of voluntary withdrawal behavior. While institutional commitment, academic performance, finance attitudes, and student perceptions of faculty concern for student development and teaching discriminated between persisters and dropouts, only final institutional commitment and final goal commitment discriminated between persisters and transfers.An earlier version of this paper was presented before the 1990 American Educational Research Association annual meeting.     

Early Relationship Quality From Home to School: A Longitudinal Study

The aim of this investigation was to examine the role of social relationships in the home as predictors of social functioning in the first years of school. Longitudinal data gathered on 156 children from urban, low-income families were used to examine the unique contributions of mother-child attachment classification at ages 1 and 2 years, the child's relationship with another adult caregiver, the child's closeness to a sibling, and the child's status in the family relative to siblings between ages 3 and 4 years, to teacher reports of their own relationship to the child and the child's social skills in the classroom and peer relations. The role of family-based relationships as possible protective factors for children at social or demographic risk for problems in school was also tested. Results indicate that quality of different family relationships provides relatively independent and complementary information about early social functioning in school, with more limited evidence for compensatory or protective processes at work.