Disentanglement and decoherence in a pair of qutrits under dephasing noise

We relate disentanglement and decoherence rates in a pair of three-level atoms subjected to multi-local and collective pure dephasing noise acting in a preferred basis. The bipartite entanglement decay rate, as bounded from above by the negativity, is found to be greater than or equal to the dephasing-decoherence rates characterized by the decay of off-diagonal elements in the corresponding full density matrix describing the system or the reduced density matrix describing either qutrit, extending previous results for qubit pairs subject to such noise.Comment: 9 pages, submitted to J. Mod. Opt. 01/21/07, accepted 08/14/07 Version 2 corrections: 1) E and D operators in second-to-last paragraph of Sec. 2. 2) matrix elements (8,6) and (9,1) in Eq.

Community Building With And For Teachers At The Math Forum

This chapter addresses the way in which the Internet forms the core of an intentional, online community by promoting communication between interested parties. The Math Forum (mathforum.org) is a unique group of individuals who are committed to using computers and the Internet to enhance what they know about learning, teaching, and doing mathematics. The Math Forum includes programmers, project and service staff, Web persons, and an ever-expanding number of teachers, students, and other individuals (i.e., parents, software developers, mathematicians). Thus, community building for The Math Forum staff includes work with teachers, with partners (National Council of the Teachers of Mathematics, Mathematics Association of America, and so on), and with specific services developed by The Math Forum staff that enable teachers and students to come together to pose and seek solutions to problems. The Math Forum uses the Internet to provide interactive services that foster mathematical thinking and discussion. These services include Ask Dr. Math and several Problems of the Week (PoWs); a teacher discussion format called Teacher to Teacher (T2T); an archive of problems, participant contributions (e.g., lesson plans), and past discussions; and an Internet newsletter. Within four years, with no explicit efforts to garner promotion or publicity, the site grew to include 1,600,000 Web pages and to attract 3.5 million accesses and over 800,000 visitors per month – a third of which constitutes sticky traffic ranging from world-famous mathematicians to elementary school children

The Centrality Of Culture And Community To Participant Learning At And With The Math Forum

In this chapter, the terms culture and community are problematized, and their centrality to participant learning at and with The Math Forum (mathforum.org) is discussed. Culture, as it is used here, refers to the rituals and norms that come to be associated with a site and its functioning. Community describes recognition of connections to and identification with other participants. The Math Forum is an interactive and inquiry-informed digital library, or virtual resource center, for mathematics education. Previous chapters have addressed the ways in which The Math Forum has leveraged the concept of community in order to become a dynamic and resource-rich educational site (Renninger & Shumar, 2002; Shumar & Renninger, 2002). In the present chapter, this analysis is taken a step further. The culture of The Math Forum is described as providing its participants with a unique set of opportunities for learning and for making the relationship between the individual and the community one in which individual and community needs can both be met. Site culture enables contributions from individuals that by definition help to build out and sustain this community. Math Forum participants include Math Forum staff members and a mix of teachers, students, and other individuals such as parents, software developers, mathematicians, math educators, professionals, and tradespeople, many of whom also volunteer their time as mentors for the site. Participants differ not only in terms of their roles, but in their experience, level of expertise, and interest for mathematics (Renninger & Shumar, 2002)

The Changing Face of Medicine: Women Doctors and the Evolution of Health Care in America

[Excerpt] This book is a case study of one profession that plays a key role in the health care sector, which now represents about one seventh of the U.S. economy. It examines the most dramatic demographic change in this sector in the last century. But the issues we raise are likely to be of interest more broadly for what they say about the changing roles of women in contemporary society. Women\u27s entry into medicine is taken as dramatic evidence that the barriers to opportunity for women are rapidly falling in America. Does the experience of female physicians to date bear out this optimistic view? An alternative view is that gender roles remain deeply entrenched in our institutions and culture. Specifically, the gender division of household labor continues to constrain the choices of all women. The trade-offs between work and family may be clearest in the most demanding professions, such as law and medicine, which require a high degree of professional devotion. Our study builds on the fine histories of women in medicine written by Walsh, Morantz-Sanchez, and More. The analysis presented here focuses on the period since 1970, thus complementing the important studies of Bowman and colleagues and Bickel. Lorber examined the experiences of the generation of women who pioneered the transformation of the profession. With the benefit of additional decades of perspective, we are in a position to examine whether the role of gender in medicine is changing

How Parents Use Time and Money

[Excerpt] This article examines weekday resource allocation decisions of married couples with a husband employed full time and with children under 18. These decisions relate, among other things, to working for pay; doing unpaid household work; purchasing services such as childcare, laundry and drycleaning, and food away from home; and eating out. Information about spending decisions was obtained from the 2009 Consumer Expenditure Survey (CE) and information about time use was obtained from the 2009 American Time Use Survey (ATUS). Results show that, Regardless of employment status, wives were more likely than husbands to spend time in household activities. On an average weekday, married fathers spent more time working than married mothers did, even married mothers employed full time. The proportion of families reporting childcare expenses and the average amount spent by those reporting were highest for families with full-time working wives and lowest for families with wives not employed for pay. Consistent with other research, working-wife families did not spend more on housekeeping and laundry services than did families with wives not employed for pay. Families with full-time working wives spent the greatest dollar amount on food away from home, but there was no significant difference in spending between families with part-time working wives and families with wives not employed for pay