Tuning bubbly structures in microchannels

Foams have many useful applications that arise from the structure and size distribution of the bubbles within them. Microfluidics allows for the rapid formation of uniform bubbles, where bubble size and volume fraction are functions of the input gas pressure, liquid flow rate, and device geometry. After formation, the microchannel confines the bubbles and determines the resulting foam structure. Bubbly structures can vary from a single row ("dripping"), to multiple rows ("alternating"), to densely packed bubbles ("bamboo" and dry foams). We show that each configuration arises in a distinct region of the operating space defined by bubble volume and volume fraction. We describe the boundaries between these regions using geometric arguments and show that the boundaries are functions of the channel aspect ratio. We compare these geometric arguments with foam structures observed in experiments using flow-focusing, T-junction, and co-flow designs to generate stable nitrogen bubbles in aqueous surfactant solution and stable droplets in oil containing dissolved surfactant. The outcome of this work is a set of design parameters that can be used to achieve desired foam structures as a function of device geometry and experimental control parameters.     

How do pre-kindergarteners spend their time? Gender,ethnicity, and income as predictors of experiences in pre-kindergarten classrooms

The current paper considers how children spend their time in state-funded pre-kindergarten programs and how time use relates to ethnicity, gender, and family income, based on the assumption that how time is spent in pre-kindergarten is relevant for the programs’ success in narrowing achievement gaps. Classroom observations of 2061 children in 652 pre-k programs in 11 states were analyzed. Findings indicated that the pre-kindergarten day was roughly equally divided among free choice, teacher-assigned activities, and meals/routines. Children spent much of their time in language/literacy, social studies, and art, and less time in math and gross motor activities. Much of the pre-k day was spent in ‘no coded learning activity.’ Children in classes with lower proportions of Latino and African American children and higher average income-to-need ratios were generally engaged in richer and more stimulating experiences. The child-level variables of ethnicity and income were generally unrelated to how children spent their time, above and beyond the effects of classroom-level ethnicity and income. There were generally small, but significant gender differences – always in the gender-stereotyped direction – in how time was spent, especially during free choice time.     

The relative effects of group size on reading progress of older students with reading difficulties

This study reports findings on the relative effects from a yearlong secondary intervention contrasting large-group, small-group, and school-provided interventions emphasizing word study, vocabulary development, fluency, and comprehension with seventh- and eighth-graders with reading difficulties. Findings indicate that few statistically significant results or clinically significant gains were associated with group size or intervention. Findings also indicate that a significant acceleration of reading outcomes for seventh- and eighth-graders from high-poverty schools is unlikely to result from a 50 min daily class. Instead, the findings indicate, achieving this outcome will require more comprehensive models including more extensive intervention (e.g., more time, even smaller groups), interventions that are longer in duration (multiple years), and interventions that vary in emphasis based on specific students’ needs (e.g., increased focus on comprehension or word study).     

Intervention Provided to Linguistically Diverse Middle School Students with Severe Reading Difficulties

This study investigated the effectiveness of a multicomponent reading intervention implemented with middle school students with severe reading difficulties, all of whom had received remedial and/or special education for several years with minimal response to intervention. Participants were 38 students in grades 6-8 who had severe deficits in word reading, reading fluency, and reading comprehension. Most were Spanish-speaking English language learners (ELLs) with identified disabilities. Nearly all demonstrated severely limited oral vocabularies in English and, for ELLs, in both English and Spanish. Students were randomly assigned to receive the research intervention (n = 20) or typical instruction provided in their school's remedial reading or special education classes (n = 18). Students in the treatment group received daily explicit and systematic small-group intervention for 40 minutes over 13 weeks, consisting of a modified version of a phonics-based remedial program augmented with English as a Second Language practices and instruction in vocabulary, fluency, and comprehension strategies. Results indicated that treatment students did not demonstrate significantly higher outcomes in word recognition, comprehension, or fluency than students who received the school's typical instruction and that neither group demonstrated significant growth over the course of the study. Significant correlations were found between scores on teachers' ratings of students' social skills and problem behaviors and posttest decoding and spelling scores, and between English oral vocabulary scores and scores in word identification and comprehension. The researchers hypothesize that middle school students with the most severe reading difficulties, particularly those who are ELLs and those with limited oral vocabularies, may require intervention of considerably greater intensity than that provided in this study. Further research directly addressing features of effective remediation for these students is needed.     

What is Program Evaluation? Generating Knowledge for Improvement

In this introductory article, we discuss the nature of Program Evaluation, describing the concepts that underlie our formal and informal evaluative efforts. Program Evaluation, like any deliberate inquiry process, is about learning. The process explicates program purposes, activities, and outcomes and generates knowledge about their merit and worth. This knowledge can inform planning and lead to program improvement. We present and discuss various definitions of Program Evaluation, focussing on its purposes and uses. We also provide an overview of the inquiry process, grounding the search for merit and worth in the American Evaluation Association's Guiding Principles for Evaluators. Because program evaluations are typically conducted to inform decision makers, we discuss aspects of professional practise that contribute to the use of an evaluation. This chapter draws heavily on previous work by Sharon Rallis and Gretchen Rossman; see the following references. Rallis, S.F. and Rossman, G.B., “Mixed Methods in Evaluation Contexts: A Pragmatic framework”, in A. Tashakkori and C. Teddlie (eds.),Handbook of Mixed Methods in the Social and Behavioral Sciences (Thousand Oaks: Sage, 2002). Rallis, S.F. and Rossman, G.B., “Communicating Quality and Qualities: The Role of the Evaluator as Critical Friend”, in A.P. Benson, D.M. Hinn and C. Lloyd (eds.),Visions of Quality: How Evaluators Define, Understand, and Represent Program Quality (Oxford: JAI Press, 2001), pp. 107–120. Rallis, S.F. and Rossman, G.B. “Dialogue for Learning: Evaluator as Critical Friend”, in R. Hopson and M.Q. Patton (eds.),How and Why Language Matters in Evaluation, New Directions for Evaluation, 86 (San Francisco: Jossey-Bass, 2000). Rossman, G.B. and Rallis, S.F.,Learning in the Field: An Introduction to Qualitive Research, 2nd edition (Thousand Oaks: Sage, 2003). Rossman, G.B. and Rallis, S.F., “Evaluation as Learning: Critical Inquiry and Use as Action”, in V.J. Caracelli and H. Preskill (eds.),The Expanding Scope of Evaluation Use, New Directions in Evaluation 88 (San Francisco: Jossey Bass, 2000).     

Creativity and the Design Process

This research examined the role of creativity in the process of designing human resource development (HRD) interventions. Both qualitative and quantitative methods were used to study the preferences and practices of ten experienced HRD practitioners. Results include a comparison of the subjects' creativity styles/preferences using the Myers‐Briggs Type Indicator and the Kirton Adaption Innovation Inventory as well as a model derived from the data, which describes the creative process used by the subjects. The phases include: 1) diagnosis, 2) immersion, 3) percolation, 4) “aha,” and 5) checking. This model focuses on how creativity is used to make design decisions. The design process used by the subjects in this research is similar to a generic creativity model. However, it includes an extensive preliminary diagnostic phase in which the HRD practitioner explores the business need, searches for the root cause of the problem, and establishes a collaborative relationship with stakeholders in the organization.     

Transfer of Learning From An Action Reflection Learning™ Program*

Learning transfer from training and development programs to the workplace is a central issue of concern for human resource development specialists. Action Reflection Learning™ (ARL™) is a form of action learning that places emphasis on the development of targeted competencies while teams of participants work on real problems which have been given to them by a sponsor. This article examines the kinds of learning and learning transfer that took place in an international food company that was striving to become a global organization. Data were collected through both field observation and formal interviews and analyzed by a team of researchers. Conclusions about the degree of transfer and the mechanisms and process supporting it are presented.     

Planning HRD Interventions; What,Why, and How

There is a large body of literature on the instructional design process but little information about the planning practices of Human Resource Development (HRD) practitioners, those who may be devising training or organization development interventions. This article describes qualitative research conducted on the planning processes of five experienced HRD practitioners. Results indicate that subjects had similar mental models of the planning process, portraying the general framework as: a) discerning the desired outcomes, b) understanding the current situation, and c) designing a process to meet the needs. They characterized the planning process as holistic and iterative, involving the use of scenarios, and paradoxical in nature. This paper will identify how the subjects' values, beliefs, and principles of practice influenced their planning. It will also describe techniques used by the subjects to enhance their planning, which involved activating internal resources (prior experience), seeking external resources (reading, talking to others), and tapping into their subconscious for insights or answers. Implications for education, practice, and further research on the planning practices of HRD practitioners will be proposed.     

A preliminary evaluation of the associations among functional performance tasks and quality of life in obese and healthy weight youth

The associations among lower extremity functional performance and quality of life in obese youth are unknown. The aims of this study were to compare lower extremity strength, lower extremity functional performance, and health related quality of life between obese and healthy-weight youth and evaluate the relationships between lower extremity performance and health related quality of life in obese youth. Twenty obese and 20 age and sex matched healthy-weight youth were recruited. Peak torque of the major lower extremity muscles were measured. Functional performance was measured with single leg hop and single leg balance tests. The Paediatric Quality of Life questionnaire's physical and psychosocial health subscales were used. Paired t-tests and multiple regression analyses were performed. Obese youth demonstrated decreased peak torque in all muscles measured (P < 0.05), poorer functional performance (P < 0.05), and worse physical health related quality of life (P < 0.05) compared to healthy-weight youth. Lower extremity functional performance was associated with aspects of quality of life in the obese group (P = 0.002), but not in the healthy-weight group (P < 0.05). These results may assist in encouraging best practices in the promotion of exercise, physical activity, and quality of life in obese youth.