Irreducible compositions and the first return to the origin of a random walk

Let $n = b_1 + ... + b_k = b_1' + \cdot + b_k'$ be a pair of compositions of $n$ into $k$ positive parts. We say this pair is {\em irreducible} if there is no positive $j < k$ for which $b_1 + ... b_j = b_1' + ... b_j'$. The probability that a random pair of compositions of $n$ is irreducible is shown to be asymptotic to $8/n$. This problem leads to a problem in probability theory. Two players move along a game board by rolling a die, and we ask when the two players will first coincide. A natural extension is to show that the probability of a first return to the origin at time $n$ for any mean-zero variance $V$ random walk is asymptotic to $\sqrt{V/(2 \pi)} n^{-3/2}$. We prove this via two methods, one analytic and one probabilistic

Social Impact

From the Dean: Our Work in this Economy.; Interview: Q&A with Paul C. Brophy; Bookshelf: Understanding Assets: Two new books explore the impact of ownership and assets on individuals and communities; Perspectives with Matthew Kreuter: Communication Connections; Building a New Paradigm: Transdisciplinary Research Comes to the Forefront; A Sense of Place: Place-Based Initiatives Help Communities and Students; Notebook: Research: Tutoring Produces Big Gains in Student Learning; Notebook: Research: Free Exercise and Nutrition Program in Brazil Could Serve as Model in United States; Notebook: Research: Growing Problem for Veterans-Domestic Violence; Notebook: Message of Service Drives Surge in Peace Corps Applications; Notebook: Research: Black Newspapers Used as Cancer Education Tool in African American Communities; Notebook: Partnerships: Indian Immersion: 22-day Exchange Offers Insight into Mental Health and Poverty; Notebook: New on the Web: Creating Community: New Online Resources; Notebook: Faculty News; Alumni News and Note

Social Impact

From the Dean: Challenging Our Profession; Perspectives: In The News: Social Work Faculty and Alumni Comment on Latina Mental Health, Saving in China, and the Poverty Line.; Bookshelf: From the Internet to Economics: What Faculty and Staff are Reading.; Perspectives by Arlene Rubin Stiffman: Indictment of Cruelty or Testimony of the Human Spirit?; Perspectives with Gina Chowa: Student Exports Poverty-Fighting Idea to Africa; Interview: Q&A with Richard A. Gephardt; Perspectives: A Closer Look at Immigration with Luis H. Zayas; 16 For Love or Money: The Rise of For-Profit Social Services.; The 4-2-1 Phenomenon: New Partnership Explores Aging in China.; Anything but Ordinary: A New View of Federal Service Presidential Management Fellows program offers solution to federal workforce challenge.; Notebook: Research: Traditional healers are legitimate resources for youth in American Indian communities, says mental health expert; Notebook: Research: Quality of care varies for older adults with depression; Notebook: Faculty News; Notebook: Conferences, Events, and Scholarships; Library Services: A resource for all of social work; Alumni News and Note

Social Impact

From the Dean: Remember the Past. Imagine the Future. Celebrate Today.; Perspectives: Temperature Rising: Health Care Reform is Back; Bookshelf: From Incentives to Intuition: What Faculty and Staff are Reading.; Perspectives with Melissa Jonson-Reid & Brett Drake: Changing the Role of Child Welfare; Perspectives: SEED for Oklahoma Kids.; Interview: Q&A with Julian Le Grand; Connecting Individual Health with Public Health: New interdisciplinary approaches are needed to solve today\u27s health care challenges. The solution lies at the nexus of social work, public health, and medicine.; The Green Dream: The social work profession has been slow to engage the issue of environmental justice, but a student-led initiative may spark new interest.; Serving Soldiers: The needs of returning veterans have changed, which has opened opportunities for new collaborations between schools of social work and the Department of Veterans Affairs.; Notebook: Research: Examining and identifying barriers to type 2 diabetes management among adolescents, key to reducing risk of complications; Notebook: Research: Study shows autism symptoms can improve into adulthood.; Notebook: Faculty News; Notebook: Events; Celebrate Our Histor

Social Impact

From The Dean: Celebrating Social Work\u27s Impact; Perspectives: In the News & Bookshelf; Making a Medicare Part D Decision; Three Quarters of Americans Will Experience Poverty in Their Lives; Interview: Q&A with Kristal Brent Zook; Perspectives: Before Disaster Strikes with David Gillespie; The Globalization of Social Work: How Flat Are We? Researchers and practitioners explore underlying social conditions that keep many left behind; Parents as Teachers: A Force for Good: Sue Stepleton leads growing program aimed at helping preschoolers reach their potential; Tapping into Energy of Older Americans: New retirement scenarios shift toward service; Notebook: Partnerships and Research School of Social Work, Eden Seminary to Offer Degrees Michael Sherraden Promotes Asset-Building in China; New Partnership with Teach For America Offers Incentives; Notebook: Faculty News; Notebook: Grants, Events, and Conferences; Alumni News and Note

Who Benefits From Teams? Comparing Workers, Supervisors, and Managers

This paper offers a political explanation for the diffusion and sustainability of team-based work systems by examining the differential outcomes of team structures for 1200 workers, supervisors, and middle managers in a large unionized telecommunications company. Regression analyses show that participation in self-managed teams is associated with significantly higher levels of perceived discretion, employment security, and satisfaction for workers and the opposite for supervisors. Middle managers who initiate team innovations report higher employment security, but otherwise are not significantly different from their counterparts who are not involved in innovations. By contrast, there are no significant outcomes for employees associated with their participation in offline problem-solving teams

Complete Genome Sequence of the Complex Carbohydrate-Degrading Marine Bacterium, Saccharophagus degradans Strain 2-40T

The marine bacterium Saccharophagus degradans strain 2-40 (Sde 2-40) is emerging as a vanguard of a recently discovered group of marine and estuarine bacteria that recycles complex polysaccharides. We report its complete genome sequence, analysis of which identifies an unusually large number of enzymes that degrade >10 complex polysaccharides. Not only is this an extraordinary range of catabolic capability, many of the enzymes exhibit unusual architecture including novel combinations of catalytic and substrate-binding modules. We hypothesize that many of these features are adaptations that facilitate depolymerization of complex polysaccharides in the marine environment. This is the first sequenced genome of a marine bacterium that can degrade plant cell walls, an important component of the carbon cycle that is not well-characterized in the marine environment

Imaging biomarker roadmap for cancer studies.

Imaging biomarkers (IBs) are integral to the routine management of patients with cancer. IBs used daily in oncology include clinical TNM stage, objective response and left ventricular ejection fraction. Other CT, MRI, PET and ultrasonography biomarkers are used extensively in cancer research and drug development. New IBs need to be established either as useful tools for testing research hypotheses in clinical trials and research studies, or as clinical decision-making tools for use in healthcare, by crossing 'translational gaps' through validation and qualification. Important differences exist between IBs and biospecimen-derived biomarkers and, therefore, the development of IBs requires a tailored 'roadmap'. Recognizing this need, Cancer Research UK (CRUK) and the European Organisation for Research and Treatment of Cancer (EORTC) assembled experts to review, debate and summarize the challenges of IB validation and qualification. This consensus group has produced 14 key recommendations for accelerating the clinical translation of IBs, which highlight the role of parallel (rather than sequential) tracks of technical (assay) validation, biological/clinical validation and assessment of cost-effectiveness; the need for IB standardization and accreditation systems; the need to continually revisit IB precision; an alternative framework for biological/clinical validation of IBs; and the essential requirements for multicentre studies to qualify IBs for clinical use.Development of this roadmap received support from Cancer Research UK and the Engineering and Physical Sciences Research Council (grant references A/15267, A/16463, A/16464, A/16465, A/16466 and A/18097), the EORTC Cancer Research Fund, and the Innovative Medicines Initiative Joint Undertaking (grant agreement number 115151), resources of which are composed of financial contribution from the European Union's Seventh Framework Programme (FP7/2007-2013) and European Federation of Pharmaceutical Industries and Associations (EFPIA) companies' in kind contribution