1,410 results on '"Wandersman A"'
Search Results
2. How to make and trap a pseudo-vesicle with a micropipette
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Tapie, Pierre, Prevost, Alexis M., Montel, Lorraine, Pontani, Léa-Laetitia, and Wandersman, Elie
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Condensed Matter - Soft Condensed Matter ,Physics - Biological Physics ,Physics - Instrumentation and Detectors - Abstract
We present a simple method to produce giant lipid pseudo-vesicles (vesicles with an oily cap on the top), trapped in an agarose gel. The method can be implemented using only a regular micropipette and relies on the formation of a water/oil/water double droplet in liquid agarose. We characterize the produced vesicle with fluorescence imaging and establish the presence and integrity of the lipid bilayer by the successful insertion of {\alpha}-Hemolysin transmembrane proteins. Finally, we show that the vesicle can be easily mechanically deformed, non-intrusively, by indenting the surface of the gel.
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- 2022
3. Impact of an individualized pain plan to treat sickle cell disease vaso-occlusive episodes in the emergency department
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Hodges, Jason, Carroll, Yvonne, Smeltzer, Matthew, Nwosu, Chinonyelum, Gurney, James, Potter, Jerlym, Badawy, Sherif, Estepp, Jeremie, Treadwell, Marsha, Vichinsky, Elliott, Wun, Ted, Potter, Michael, Hessler, Danielle, Hagar, Ward, Marsh, Anne, Neumayr, Lynne, Melvin, Cathy, Kanter, Julie, Phillips, Shannon, Adams, Robert, Mueller, Martina, Davila, Caroline, Nirmish Shah, Sarah Bourne., Tanabe, Paula, Bosworth, Hayden, Jackson, George, Richesson, Rachel, Prvu-Bettger, Janet, Masese, Rita, DeMartino, Terri, Kutlar, Abdullah, Gibson, Robert, Snyder, Angela, Fernandez, Maria, Lyon, Matthew, Lottenberg, Richard, Lawrence, Raymona, Gollan, Sierra, Bowman, Latanya, Richardson, Lynne, Glassberg, Jeffrey, Simon, Jena, Loo, George T., Clesca, Cindy, Linton, Elizabeth, Ryan, Gery, Gordeuk, Victor, Hirschtick, Jana, Hsu, Lewis, Krishnan, Jerry, Wandersman, Abe, Colla, Joe, Erwin, Kim, Lamont, Andrea, Norell, Sarah, Saving, Kay, Nocek, Judith, King, Allison, Baumann, Ana, Calhoun, CeCe, Luo, Lingzi, James, Aimee, Abel, Regina, Varughese, Taniya, Kroner, Barbara, Rojas-Smith, Lucia, Hendershot, Tabitha, DiMartino, Lisa, Jacobs, Sara, Battestilli, Whitney, Brambilla, Don, Cox, Lisa, Preiss, Liliana, Pugh, Norma, Telfair, Joseph, Hassell, Kathryn, Thompson, Alexis, Tompkins, William, Smith, Sharon, Luksenberg, Harvey, Peters-Lawrence, Marlene, Boyce, Cheryl, Barfield, Whitney, Werner, Ellen, Siewny, Lauren, Melvin, Cathy L., Carpenter, Christopher R., Hankins, Jane S., Colla, Joseph S., Davila, Natalia, Masese, Rita V., McCuskee, Sarah, and Gollan, S. Siera
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- 2024
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4. Improving Sexual Assault and Sexual Harassment Prevention from the Bottom-up: a Pilot of Getting To Outcomes in the US Military
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Chinman, Matthew, Acosta, Joie, Bush-Mecenas, Susan, Smucker, Sierra, Farris, Coreen, Fortson, Beverly, Imm, Pamela, Lamont, Andrea, Maguire, Thomas, Martin, Laurie, Wandersman, Abraham, Watson, Amber, Wicker, Amanda, and Tharp, Andra
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- 2023
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5. Using cognitive interviews to improve a measure of organizational readiness for implementation
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McClam, Maria, Workman, Lauren, Dias, Emanuelle M., Walker, Timothy J., Brandt, Heather M., Craig, Derek W., Gibson, Robert, Lamont, Andrea, Weiner, Bryan J., Wandersman, Abraham, and Fernandez, Maria E.
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- 2023
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6. A simple method to make, trap and deform a vesicle in a gel
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Tapie, Pierre, Prevost, Alexis M., Montel, Lorraine, Pontani, Léa-Laetitia, and Wandersman, Elie
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- 2023
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7. Implementation Science in Thailand: Design and Methods of a Geriatric Mental Health Cluster-Randomized Trial.
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Gallagher-Thompson, Dolores, Tongsiri, Sirinart, Wisetpholchai, Bussabong, Fritz, Stacy, Lamont, Andrea, Domlyn, Ariel, Wandersman, Abraham, Marques, Andrea, Chen, Hongtu, Levkoff, Sue, Chuengsatiansup, Komatra, Sihapark, Siranee, and Hinton, Ladson
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Behavioral problem ,Thailand ,dementia ,elderly ,implementation science ,intervention ,Aged ,Caregivers ,Dementia ,Humans ,Implementation Science ,Mental Health ,Thailand - Abstract
BACKGROUND: Thailand has a rapidly aging population yet lacks evidence for effective and scalable evidence-based psychosocial interventions to support persons living with dementia and their family caregivers. In this study of a culturally adapted and evidence-based clinical program (Reducing Disabilities in Alzheimers Disease [RDAD]), designed to reduce behavioral and psychological symptoms of dementia in older adults, the authors test the hypothesis that an implementation support strategy, Getting To Outcomes (GTO), would produce better implementation and clinical outcomes compared with usual implementation of RDAD in Thailand. METHODS: The study uses a hybrid type III cluster-randomized design to compare eight geographical districts that receive training on both implementing the RDAD clinical intervention and on GTO implementation support strategies (intervention arm) with eight other districts that receive the same RDAD training but without training in GTO implementation support strategies (control arm). GTO is an evidence-based intervention designed to support implementers to better plan, implement, and evaluate innovative intervention programs in a novel setting. Primary outcomes, including implementation and clinical outcomes, will be assessed at baseline, month 3 (posttreatment), and month 6 (3-month follow-up). RESULTS: The research team anticipates that there will be significantly more improvements in the delivery of the RDAD intervention program in the experimental group than in the control group. NEXT STEPS: If clinical trial findings are positive, the authors plan to replicate and scale up the proposed implementation science approach across Thailand to enhance and expand mental health services for older adults with dementia.
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- 2022
8. Adhesion as a trigger of droplet polarization in flowing emulsions
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Golovkova, Iaroslava, Montel, Lorraine, Pan, Franck, Wandersman, Elie, Prevost, Alexis M., Bertrand, Thibault, and Pontani, Léa-Laetitia
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Condensed Matter - Soft Condensed Matter - Abstract
Tissues are subjected to large external forces and undergo global deformations during morphogenesis. We use synthetic analogues of tissues to study the impact of cell-cell adhesion on the response of cohesive cellular assemblies under such stresses. In particular, we use biomimetic emulsions in which the droplets are functionalized in order to exhibit specific droplet-droplet adhesion. We flow these emulsions in microfluidic constrictions and study their response to this forced deformation via confocal microscopy. We find that the distributions of avalanche sizes are conserved between repulsive and adhesive droplets. However, adhesion locally impairs the rupture of droplet-droplet contacts, which in turn pulls on the rearranging droplets. As a result, adhesive droplets are a lot more deformed along the axis of elongation in the constriction. This finding could shed light on the origin of polarization processes during morphogenesis., Comment: 10 pages, 5 figures
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- 2021
9. A bending fluctuation-based mechanism for particle detection by ciliated structures
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Thomazo, Jean-Baptiste, Révérend, Benjamin Le, Pontani, Léa-Laetitia, Prevost, Alexis, and Wandersman, Elie
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Condensed Matter - Soft Condensed Matter ,Physics - Biological Physics ,Physics - Fluid Dynamics - Abstract
To mimic the mechanical response of passive biological cilia in complex fluids, we study the bending dynamics of an anchored elastic fiber submitted to a dilute granular suspension under shear. We show that the bending fluctuations of the fiber accurately encode minute variations of the granular suspension concentration. Indeed, besides the stationary bending induced by the continuous phase flow, the passage of each single particle induces an additional deflection. We demonstrate that the dominant particle/fiber interaction arises from direct contacts of the particles with the fiber and we propose a simple elastohydrodynamics model to predict their amplitude. Our results shed light on the extreme mechanical sensitivity of biological cilia to detect the presence of solid particles in their vicinity and bring a physical framework to describe their dynamics in particulate flows., Comment: 8 pages, 4 Figures, 1 Supplementary Material File
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- 2020
10. Collective stiffening of soft hair assemblies
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Thomazo, Jean-Baptiste, Lauga, Eric, Révérend, Benjamin Le, Wandersman, Elie, and Prevost, Alexis Michel
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Condensed Matter - Soft Condensed Matter - Abstract
Many living systems use assemblies of soft and slender structures whose deflections allow them to mechanically probe their immediate environment. In this work, we study the collective response of artificial soft hair assemblies to a shear flow by imaging their deflections. At all hair densities, the deflection is found to be proportional to the local shear stress with a proportionality factor that decreases with density. The measured collective stiffening of hairs is modeled both with a microscopic elastohydrodynamic model that takes into account long range hydrodynamic hair-hair interactions and a phenomenological model that treats the hair assemblies as an effective porous medium. While the microscopic model is in reasonable agreement with the experiments at low hair density, the phenomenological model is found to be predictive across the entire density range., Comment: 5 pages, 3 figures
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- 2020
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11. Depletion attraction favors the elastic response of emulsions flowing in a constriction
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Golovkova, Iaroslava, Montel, Lorraine, Wandersman, Elie, Bertrand, Thibault, Prevost, Alexis Michel, and Pontani, Lea-Laetitia
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Condensed Matter - Soft Condensed Matter - Abstract
We study the elasto-plastic behavior of dense attractive emulsions under mechanical perturbation. The attraction is introduced through non-specific depletion interactions between the droplets and is controlled by changing the concentration of surfactant micelles in the continuous phase. We find that such attractive forces are not sufficient to induce any measurable modification on the scalings between the local packing fraction and the deformation of the droplets. However, when the emulsions are flown through 2D microfluidic constrictions, we uncover a measurable effect of attraction on their elasto-plastic response. Indeed, we measure higher levels of deformation inside the constriction for attractive droplets. In addition, we show that these measurements correlate with droplet rearrangements that are spatially delayed in the constriction for higher attraction forces., Comment: 9 pages, 5 figures
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- 2019
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12. A multilevel mHealth intervention boosts adherence to hydroxyurea in individuals with sickle cell disease
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Hankins, Jane S., Hodges, Jason, Carroll, Yvonne, Klesges, Lisa, Khan, Hamda, Smeltzer, Matthew, Nwosu, Chinonyelum, Gurney, James, Porter, Jerlym, Alberts, Nicole, French, Reginald, Badawy, Sherif, DeBaun, Michael, Kang, Guolian, Estepp, Jeremie, Wang, Winfred, Owens, Curtis, Debon, Margaret, Osarogiagbon, Ray, Nelson, Marquita, Treadwell, Marsha, Vichinsky, Elliott, Wun, Ted, Potter, Michael, Hessler, Danielle, Hagar, Ward, Marsh, Anne, Neumayr, Lynne, Melvin, Cathy, Kanter, Julie, Phillips, Shannon, Adams, Robert, Mueller, Martina, Abrams, Tina, Davia, Nathalia, Shah, Nirmish, Tanabe, Paula, Bosworth, Hayden, Jackson, George, Johnson, Fred, Richesson, Rachel, Prvu-Bettger, Janet, King, Allison, Baumann, Ana, Calhoun, Cecilia, Kutlar, Abdullah, Gibson, Robert, Snyder, Angie, Fernandez, Maria, Lottenberg, Richard, Richardson, Lynne D., Glassberg, Jeffrey, Simon, Jena, Genes, Nicholas G., Loo, George T., Shapiro, Jason S., Souffront, Kimberly, Clesca, Cindy, Linton, Elizabeth, Ryan, Gery, Kroner, Barbara L, Hendershot, Tabitha, DiMartino, Lisa, Jacobs, Sara, Battestilli, Whitney, Brambilla, Donald, Cox, Lisa, Preiss, Liliana, Pugh, Norma, Li, Sophie, VonLehmden, Annie, Smith, Sharon M, Tonkins, William P., Peters-Lawrence, Marlene, Boyce, Cheryl, Barfield, Whitney, Thompson, Alexis, Gordeuk, Victor, Gutierrez, Melissa, Hirschtick, Jana, Hsu, Lewis, Krishnan, Jerry, Sebro, Nadew, Verda, Larissa, Wandersman, Abe, Berbaum, Michael, Bobba, Kishore, Colla, Joe, Erwin, Kim, Lamont, Andrea, Martin, Molly, Norell, Sarah, Pandit, Ananta, Saving, Kay, Shannon, Robin, Winn, Robert, Zun, Leslie, Hassan, Taif, Lasley, Patricia, Monnard, Kristin, Nocek, Judith, Roesch, Pamela, Potter, Michael B., King, Allison A., Baumann, Ana A., Gordeuk, Victor R., Hsu, Lewis L., Porter, Jerlym S., Alberts, Nicole M., Badawy, Sherif M., Glassberg, Jeffrey A., Fernandez, Maria E., Bosworth, Hayden B., and Klesges, Lisa M.
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- 2023
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13. A simple method to make, trap and deform a vesicle in a gel
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Pierre Tapie, Alexis M. Prevost, Lorraine Montel, Léa-Laetitia Pontani, and Elie Wandersman
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Medicine ,Science - Abstract
Abstract We present a simple method to produce giant lipid pseudo-vesicles (vesicles with an oily cap on the top), trapped in an agarose gel. The method can be implemented using only a regular micropipette and relies on the formation of a water/oil/water double droplet in liquid agarose. We characterize the produced vesicle with fluorescence imaging and establish the presence and integrity of the lipid bilayer by the successful insertion of $$\alpha $$ α -Hemolysin transmembrane proteins. Finally, we show that the vesicle can be easily mechanically deformed, non-intrusively, by indenting the surface of the gel.
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- 2023
- Full Text
- View/download PDF
14. Probing the in-mouth texture perception with a biomimetic tongue
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Thomazo, Jean-Baptiste, Pastenes, Javier Contreras, Pipe, Christopher, Révérend, Benjamin Le, Wandersman, Elie, and Prevost, Alexis M.
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Condensed Matter - Soft Condensed Matter - Abstract
An experimental biomimetic tongue-palate system has been developed to probe human in-mouth texture perception. Model tongues are made from soft elastomers patterned with fibrillar structures analogue to human filiform papillae. The palate is represented by a rigid flat plate parallel to the plane of the tongue. To probe the behavior under physiological flow conditions, deflections of model papillae are measured using a novel fluorescent imaging technique enabling sub-micrometer resolution of the displacements. Using optically transparent newtonian liquids under steady shear flow, we show that deformations of the papillae allow determining their viscosity from 1 Pa.s down to the viscosity of water of 1 mPa.s, in full quantitative agreement with a recently proposed model [Lauga et al., Frontiers in Physics, 2016, 4, 35]. The technique is further validated for a shear-thinning and optically opaque dairy system., Comment: 10 pages, 10 figures
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- 2019
15. Diffusion through nanopores in connected lipid bilayer networks
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Valet, Manon, Pontani, Léa-Laetitia, Voituriez, Raphaël, Wandersman, Elie, and Prevost, Alexis M.
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Physics - Biological Physics ,Condensed Matter - Soft Condensed Matter ,Quantitative Biology - Subcellular Processes - Abstract
A biomimetic model of cell-cell communication was developed to probe the passive molecular transport across ion channels inserted in synthetic lipid bilayers formed between contacting droplets arranged in a linear array. Diffusion of a fluorescent probe across the array was measured for different pore concentrations. The diffusion characteristic time scale is found to vary non-linearly with the pore concentration. Our measurements are successfully modeled by a continuous time random walk description, whose waiting time is the first exit time from a droplet through a cluster of pores. The size of the cluster of pores is found to increase with their concentration. Our results provide a direct link between the mesoscopic permeation properties and the microscopic characteristics of the pores such as their number, size and spatial arrangement., Comment: 5 pages, 3 figures
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- 2019
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16. Using cognitive interviews to improve a measure of organizational readiness for implementation
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Maria McClam, Lauren Workman, Emanuelle M. Dias, Timothy J. Walker, Heather M. Brandt, Derek W. Craig, Robert Gibson, Andrea Lamont, Bryan J. Weiner, Abraham Wandersman, and Maria E. Fernandez
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Organizational readiness ,Qualitative methods ,Cognitive interviewing ,Evidence-based interventions ,cancer prevention ,Measure development ,Public aspects of medicine ,RA1-1270 - Abstract
Abstract Background Organizational readiness is a key factor for successful implementation of evidence-based interventions (EBIs), but a valid and reliable measure to assess readiness across contexts and settings is needed. The R = MC2 heuristic posits that organizational readiness stems from an organization’s motivation, capacity to implement a specific innovation, and its general capacity. This paper describes a process used to examine the face and content validity of items in a readiness survey developed to assess organizational readiness (based on R = MC2) among federally qualified health centers (FQHC) implementing colorectal cancer screening (CRCS) EBIs. Methods We conducted 20 cognitive interviews with FQHC staff (clinical and non-clinical) in South Carolina and Texas. Participants were provided a subset of items from the readiness survey to review. A semi-structured interview guide was developed to elicit feedback from participants using “think aloud” and probing techniques. Participants were recruited using a purposive sampling approach and interviews were conducted virtually using Zoom and WebEx. Participants were asked 1) about the relevancy of items, 2) how they interpreted the meaning of items or specific terms, 3) to identify items that were difficult to understand, and 4) how items could be improved. Interviews were transcribed verbatim and coded in ATLAS.ti. Findings were used to revise the readiness survey. Results Key recommendations included reducing the survey length and removing redundant or difficult to understand items. Additionally, participants recommended using consistent terms throughout (e.g., other units/teams vs. departments) the survey and changing pronouns (e.g., people, we) to be more specific (e.g., leadership, staff). Moreover, participants recommended specifying ambiguous terms (e.g., define what “better” means). Conclusion Use of cognitive interviews allowed for an engaged process to refine an existing measure of readiness. The improved and finalized readiness survey can be used to support and improve implementation of CRCS EBIs in the clinic setting and thus reduce the cancer burden and cancer-related health disparities.
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- 2023
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17. Developing a sustainability readiness strategy for health systems: Toolkit, interactive tools, and virtual support system
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Johnson, Knowlton, Collins, David, and Wandersman, Abraham
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- 2023
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18. A bending fluctuation-based mechanism for particle detection by ciliated structures
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Thomazo, Jean-Baptiste, Le Révérend, Benjamin, Pontani, Lea-Laetitia, Prevost, Alexis M., and Wandersman, Elie
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- 2021
19. Strengthening the Science and Practice of Implementation Support: Evaluating the Effectiveness of Training and Technical Assistance Centers
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Wandersman, Abraham, primary and Scheier, Lawrence M., additional
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- 2024
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20. A scoping review of the evaluation and effectiveness of technical assistance
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Victoria C. Scott, Zara Jillani, Adele Malpert, Jenny Kolodny-Goetz, and Abraham Wandersman
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Technical assistance ,TA ,Technical assistance evaluation ,Technical assistance effectiveness ,Capacity building ,Scoping review ,Medicine (General) ,R5-920 - Abstract
Abstract Background Although the benefits of evidence-based practices (EBPs) for advancing community outcomes are well-recognized, challenges with the uptake of EBPs are considerable. Technical assistance (TA) is a core capacity building strategy that has been widely used to support EBP implementation and other community development and improvement efforts. Yet despite growing reliance on TA, no reviews have systematically examined the evaluation of TA across varying implementation contexts and capacity building aims. This study draws on two decades of peer-reviewed publications to summarize the evidence on the evaluation and effectiveness of TA. Methods Guided by Arksey and O’Malley’s six-stage methodological framework, we used a scoping review methodology to map research on TA evaluation. We included peer-reviewed articles published in English between 2000 and 2020. Our search involved five databases: Business Source Complete, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Education Resources Information Center (ERIC), PsycInfo, and PubMed. Results A total of 125 evaluation research studies met the study criteria. Findings indicate that publications have increased over the last two decades, signaling a growth in the recognition and reporting of TA. Technical assistance is being implemented across diverse settings, often serving socially vulnerable and under-resourced populations. Most evaluation research studies involved summative evaluations, with TA outcomes mostly reported at the organizational level. Only 5% of the studies examined sustainability of TA outcomes. This review also demonstrates that there is a lack of consistent standards regarding the definition of TA and the level of reporting across relevant TA evaluation categories (e.g., cadence of contact, and directionality). Conclusions Advances in the science and practice of TA hinge on understanding what aspects of TA are effective and when, how, and for whom these aspects of TA are effective. Addressing these core questions requires (i) a standard definition for TA; (ii) more robust and rigorous evaluation research designs that involve comparison groups and assessment of direct, indirect, and longitudinal outcomes; (iii) increased use of reliable and objective TA measures; and (iv) development of reporting standards. We view this scoping review as a foundation for improving the state of the science and practice of evaluating TA.
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- 2022
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21. A scoping review of the evaluation and effectiveness of technical assistance
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Scott, Victoria C., Jillani, Zara, Malpert, Adele, Kolodny-Goetz, Jenny, and Wandersman, Abraham
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- 2022
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22. Study protocol: cluster randomized trial of consultation strategies for the sustainment of mental health interventions in under-resourced urban schools: rationale, design, and methods
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Eiraldi, Ricardo, McCurdy, Barry L., Khanna, Muniya S., Wolk, Courtney Benjamin, Glick, Henry A., Rabenau-McDonnell, Quinn A., Comly, Rachel, Rutherford, Laura E., Banks, Jayme, Rufe, Steven A., Popkin, Kristina M., Wilson, Tara, Henson, Kathryn, Wandersman, Abraham, and Jawad, Abbas F.
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- 2022
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23. Study protocol: cluster randomized trial of consultation strategies for the sustainment of mental health interventions in under-resourced urban schools: rationale, design, and methods
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Ricardo Eiraldi, Barry L. McCurdy, Muniya S. Khanna, Courtney Benjamin Wolk, Henry A. Glick, Quinn A. Rabenau-McDonnell, Rachel Comly, Laura E. Rutherford, Jayme Banks, Steven A. Rufe, Kristina M. Popkin, Tara Wilson, Kathryn Henson, Abraham Wandersman, and Abbas F. Jawad
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Sustainment ,Implementation ,PBIS ,Mental health supports ,Urban schools ,Effectiveness ,Psychology ,BF1-990 - Abstract
Abstract Background The school is a key setting for the provision of mental health services to children, particularly those underserved through traditional service delivery systems. School-wide Positive Behavioral Interventions and Supports (PBIS) is a tiered approach to service delivery based on the public health model that schools use to implement universal (Tier 1) supports to improve school climate and safety. As our prior research has demonstrated, PBIS is a useful vehicle for implementing mental and behavioral health evidence-based practices (EBPs) at Tier 2 for children with, or at risk for, mental health disorders. Very little research has been conducted regarding the use of mental health EBPs at Tier 2 or how to sustain implementation in schools. Methods/design The main aim of the study is to compare fidelity, penetration, cost-effectiveness, and student outcomes of Tier 2 mental health interventions across 2 sustainment approaches for school implementers in 12 K-8 schools. The study uses a 2-arm, cluster randomized controlled trial design. The two arms are: (a) Preparing for Sustainment (PS)—a consultation strategy implemented by school district coaches who receive support from external consultants, and (b) Sustainment as Usual (SAU)—a consultation strategy implemented by school district coaches alone. Participants will be 60 implementers and 360 students at risk for externalizing and anxiety disorders. The interventions implemented by school personnel are: Coping Power Program (CPP) for externalizing disorders, CBT for Anxiety Treatment in Schools (CATS) for anxiety disorders, and Check-in/Check-out (CICO) for externalizing and internalizing disorders. The Interactive Systems Framework (ISF) for Dissemination and Implementation guides the training and support procedures for implementers. Discussion We expect that this study will result in a feasible, effective, and cost-effective strategy for sustaining mental health EBPs that is embedded within a multi-tiered system of support. Results from this study conducted in a large urban school district would likely generalize to other large, urban districts and have an impact on population-level child mental health. Trial registration ClinicalTrials.gov identifier number NCT04869657. Registered May 3, 2021.
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- 2022
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24. Development and pilot test of criteria defining best practices for organizational sexual assault prevention
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Acosta, Joie, Chinman, Matthew, Tharp, Andra, Baker, Jack, Flaspohler, Paul, Fortson, Beverly, Kerr, Amy, Lamont, Andrea, Meyer, Amanda, Smucker, Sierra, Wargel, Katelyn, and Wandersman, Abraham
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- 2022
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25. Quasi-static microdroplet production in a capillary trap
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Valet, M., Pontani, L. -L., Prevost, A. M., and Wandersman, E.
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Condensed Matter - Soft Condensed Matter - Abstract
We have developed a method to produce aqueous microdroplets in an oil phase, based on the periodic extraction of a pending droplet across the oil/air interface. This interface forms a capillary trap inside which a droplet can be captured and detached. This process is found to be capillary- based and quasi-static. The droplet size and emission rate are independently governed by the injected volume per cycle and the extraction frequency. We find that the minimum droplet diameter is close to the injection glass capillary diameter and that variations in surface tension moderately perturb the droplet size. A theoretical model based on surface energy minimization in the oil/water/air phases was derived and captures the experimental results. This method enables robust, versatile and tunable production of microdroplets at low production rates.
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- 2017
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26. Non-Amontons-Coulomb local friction law of randomly rough contact interfaces with rubber
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Nguyen, D. T., Wandersman, E., Prevost, A., Chenadec, Y. Le, Fretigny, C., and Chateauminois, A.
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Condensed Matter - Soft Condensed Matter - Abstract
We report on measurements of the local friction law at a multi-contact interface formed between a smooth rubber and statistically rough glass lenses, under steady state friction. Using contact imaging, surface displacements are measured, and inverted to extract both distributions of frictional shear stress and contact pressure with a spatial resolution of about 10~$\mu$m. For a glass surface whose topography is self-affine with a Gaussian height asperity distribution, the local frictional shear stress is found to vary strongly sub-linearly with the local contact pressure over the whole investigated pressure range. Such sub-linear behavior is also evidenced for a surface with a non Gaussian height asperity distribution, demonstrating that, for such multi-contact interfaces, Amontons-Coulomb's friction law does not prevail at the local scale.
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- 2017
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27. Normal contact and friction of rubber with model randomly rough surfaces
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Yashima, S., Romero, V., Wandersman, E., Frétigny, C., Chaudhury, M. K., Chateauminois, A., and Prevost, A. M.
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Condensed Matter - Soft Condensed Matter - Abstract
We report on normal contact and friction measurements of model multicontact interfaces formed between smooth surfaces and substrates textured with a statistical distribution of spherical micro-asperities. Contacts are either formed between a rigid textured lens and a smooth rubber, or a flat textured rubber and a smooth rigid lens. Measurements of the real area of contact $A$ versus normal load $P$ are performed by imaging the light transmitted at the microcontacts. For both interfaces, $A(P)$ is found to be sub-linear with a power law behavior. Comparison to two multi-asperity contact models, which extend Greenwood-Williamson (J. Greenwood, J. Williamson, \textit{Proc. Royal Soc. London Ser. A} \textbf{295}, 300 (1966)) model by taking into account the elastic interaction between asperities at different length scales, is performed, and allows their validation for the first time. We find that long range elastic interactions arising from the curvature of the nominal surfaces are the main source of the non-linearity of $A(P)$. At a shorter range, and except for very low pressures, the pressure dependence of both density and area of micro-contacts remains well described by Greenwood-Williamson's model, which neglects any interaction between asperities. In addition, in steady sliding, friction measurements reveal that the mean shear stress at the scale of the asperities is systematically larger than that found for a macroscopic contact between a smooth lens and a rubber. This suggests that frictional stresses measured at macroscopic length scales may not be simply transposed to microscopic multicontact interfaces.
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- 2017
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28. Important Implementation Constructs for Federal Agencies in Health and Human Service Settings That Are Selecting, Monitoring, and Supporting Grantees
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Dymnicki, Allison, Bzura, Robin, Osher, David, Wandersman, Abraham, Duplantier, Dan, Boyd, Michelle, Cash, Amanda, and Hutchison, Lindsey
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Background: Federal agencies and other funders seeking to maximise their impact aim to understand factors associated with implementing evidence-based interventions (EBIs) to address health problems. Challenges exist, however, in synthesising information from different disciplines and reaching agreement about these factors due to different terminology, frameworks, and measures being used in different fields. Methods: A mixed-methods approach was used to identifying a set of implementation constructs helpful for selecting, monitoring, and supporting federal grantees in health and human service settings. Three phases of research were conducted: a literature review, structured expert interviews, and consensus building. Interviews with implementation experts were used to validate a set of implementation constructs identified in the literature review as strongly and consistently related to successful implementation of EBIs in international contexts. A modified Delphi approach was used with a technical working group (TWG) of federal staff to agree on the constructs most relevant for federally funded EBIs. Findings: This process yielded 11 constructs related to either the intervention, the intersection between the invention and context, or the implementation process. These constructs are areas of interest when integrating research evidence into routine practice. Expert interviewees recommended establishing clear, consistent construct definitions before developing valid, feasible measures of the constructs. In contrast to the numerous and specific constructs advanced by researchers, federal TWG members favoured fewer constructs with more generalisability. Discussion and conclusions: This article demonstrates the translation work required for policy contexts and highlights a successful approach to translate evidence from implementation science research for federal staff.
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- 2020
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29. Formative Evaluation and Complex Health Improvement Initiatives: A Learning System to Improve Theory, Implementation, Support, and Evaluation
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Scott, V. C., Alia, K., Scaccia, J., Ramaswamy, R., Saha, S., Leviton, L., and Wandersman, A.
- Abstract
Sustainable community health improvement often requires the implementation of complex interventions in complex systems. Drawing from the "Four Keys to Success" frame (theory, implementation, support, and evaluation), this article describes how we used a formative evaluation approach to foster a learning system capable of monitoring and addressing emerging community needs within the Spreading Community Accelerators Through Learning and Evaluation (SCALE) initiative--a national capacity-building effort to support 24 community coalitions' progress toward a Culture of Health. The formative evaluation approach resulted in critical advancements to the theory, implementation, and nature of supports provided in SCALE. These improvements enabled the SCALE evaluation team to shift from the initial focus on program implementation issues to a greater emphasis on downstream factors (community-level outcomes). The ability of formative evaluation to grapple with the emerging challenges of implementing complex interventions in complex systems makes it particularly valuable for community health improvement initiatives.
- Published
- 2020
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30. Soft Lithography using Nectar Droplets
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Biswas, Saheli, Chakrabarti, Aditi, Chateauminois, Antoine, Wandersman, Elie, Prevost, Alexis M., and Chaudhury, Manoj K.
- Subjects
Condensed Matter - Soft Condensed Matter - Abstract
In spite of significant advances in replication technologies, methods to produce well-defined three dimensional structures are still at its infancy. Such a limitation would be evident if we were to produce a large array of simple and, especially, compound convex lenses, also guaranteeing that their surfaces would be molecularly smooth. Here, we report a novel method to produce such structures by cloning the 3D shape of nectar drops, found widely in nature, using conventional soft lithography.The elementary process involves transfer of a thin patch of the sugar solution coated on a glass slide onto a hydrophobic substrate on which this patch evolves into a microdroplet. Upon the absorption of water vapor, such a microdroplet grows linearly with time and its final size can be controlled by varying its exposure time to water vapor. At any stage of the evolution of the size of the drop, its shape can be cloned onto a soft elastomer by following the well-known methods of molding and crosslinking the same. A unique new science that emerges in our attempt to understand the transfer of the sugar patch and its evolution to a spherical drop is the elucidation of the mechanics underlying the contact of a deformable sphere against a solid support intervening a thin liquid film. A unique aspect of this work is to demonstrate that higher level structures can also be generated by transferring even smaller nucleation sites on the surface of the primary lenses and then allowing them to grow by absorption of water vapor. What results at the end is either a well-controlled distribution of smooth hemispherical lenses or compound structures that could have potential applications in the fundamental studies of contact mechanics, wettability and even in optics.
- Published
- 2016
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31. Elements for successful implementation of a clinic-based health literacy intervention
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Mark M. Macauda, Michelle A. Arent, Mayank Sakhuja, Brooks Yelton, Samuel Noblet, Delores Fedrick, Diana Zona, Cyndi New, William D. Isenhower, Abraham Wandersman, and Daniela B. Friedman
- Subjects
patient-provider communication ,health literacy ,pragmatic intervention ,clinic-based implementation ,AskMe3 ,mixed methods ,Public aspects of medicine ,RA1-1270 - Abstract
Improving health literacy is a national public health priority. Given the context of the COVID-19 pandemic, it is even more critical for health and medical information to be clear and understandable for patients and their families. Clinic-based programs to improve health literacy need to be pragmatic, feasible, and helpful for the implementing clinic and patients. This paper describes the development, implementation, and evaluation of a pragmatic, clinic-based health literacy intervention in a safety-net clinic that serves uninsured and indigent patients. Study methods are guided by a previous pilot study and components recommended for pragmatic interventions. An electronic readiness assessment was distributed to out-patient clinics affiliated with a statewide hospital association. The AskMe3 tool was used for the intervention as it is evidence informed and relatively easy to implement. Implementation included ongoing dialogue between the clinic and the academic research team. Within the implementing clinic, data collected from patients via verbally administered questionnaires was analyzed using descriptive statistics and chi-squares. Interview data collected from the clinic director was analyzed qualitatively for themes. The implementing clinic had some of the lowest average scores of the 34 clinics who participated in the initial readiness assessment. Despite this, they were able to successfully implement the health literacy intervention during a global pandemic. Eighty-eight participants completed patient questionnaires at this clinic. Most patients (96%) agreed the AskMe3 questions helped them talk with the doctor or nurse at their current appointment. Most (99%) also perceived the AskMe3 tool to be very helpful when used in a clinical setting. The clinic director offered that the staff initially thought the intervention would be difficult to implement. However, implementation by clinic volunteers with encouragement and prioritization of health literacy by the clinic director contributed to success. When considering interventions for clinical settings, a pragmatic approach can help with selection and implementation of a program that fits with the realities on the ground. Further, frequent technical assistance can help resolve implementation barriers. Interventions utilizing tools such as AskMe3, because of their simplicity, allow creative solutions to capacity issues for clinics who see a need for health literacy improvements.
- Published
- 2022
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32. Impact of an individualized pain plan to treat sickle cell disease vaso-occlusive episodes in the emergency department
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Siewny, Lauren, King, Allison, Melvin, Cathy L., Carpenter, Christopher R., Hankins, Jane S., Colla, Joseph S., Preiss, Liliana, Luo, Lingzi, Cox, Lisa, Treadwell, Marsha, Davila, Natalia, Masese, Rita V., McCuskee, Sarah, Gollan, S. Siera, Tanabe, Paula, Hodges, Jason, Carroll, Yvonne, Smeltzer, Matthew, Nwosu, Chinonyelum, Gurney, James, Potter, Jerlym, Badawy, Sherif, Estepp, Jeremie, Treadwell, Marsha, Vichinsky, Elliott, Wun, Ted, Potter, Michael, Hessler, Danielle, Hagar, Ward, Marsh, Anne, Neumayr, Lynne, Melvin, Cathy, Kanter, Julie, Phillips, Shannon, Adams, Robert, Mueller, Martina, Davila, Caroline, Nirmish Shah, Sarah Bourne., Tanabe, Paula, Bosworth, Hayden, Jackson, George, Richesson, Rachel, Prvu-Bettger, Janet, Masese, Rita, DeMartino, Terri, Kutlar, Abdullah, Gibson, Robert, Snyder, Angela, Fernandez, Maria, Lyon, Matthew, Lottenberg, Richard, Lawrence, Raymona, Gollan, Sierra, Bowman, Latanya, Richardson, Lynne, Glassberg, Jeffrey, Simon, Jena, Loo, George T., Clesca, Cindy, Linton, Elizabeth, Ryan, Gery, Gordeuk, Victor, Hirschtick, Jana, Hsu, Lewis, Krishnan, Jerry, Wandersman, Abe, Colla, Joe, Erwin, Kim, Lamont, Andrea, Norell, Sarah, Saving, Kay, Nocek, Judith, King, Allison, Baumann, Ana, Calhoun, CeCe, Luo, Lingzi, James, Aimee, Abel, Regina, Varughese, Taniya, Kroner, Barbara, Rojas-Smith, Lucia, Hendershot, Tabitha, DiMartino, Lisa, Jacobs, Sara, Battestilli, Whitney, Brambilla, Don, Cox, Lisa, Preiss, Liliana, Pugh, Norma, Telfair, Joseph, Hassell, Kathryn, Thompson, Alexis, Tompkins, William, Smith, Sharon, Luksenberg, Harvey, Peters-Lawrence, Marlene, Boyce, Cheryl, Barfield, Whitney, and Werner, Ellen
- Abstract
•Both patients with sickle cell disease and ED providers strongly endorse IPPs.•Collaboration among specialties, including informatics and patients, is needed to successfully implement IPPs.
- Published
- 2024
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33. The Readiness, Resilience and Recovery Tool: An Emerging Approach to Enhance Readiness Amidst Disruption
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Kolodny-Goetz, Jennifer, Hamm, Debra W., Cook, Brittany S., and Wandersman, Abraham
- Published
- 2021
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34. Using Implementation Mapping to Build Organizational Readiness
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Amber K. Watson, Belinda F. Hernandez, Jenny Kolodny-Goetz, Timothy J. Walker, Andrea Lamont, Pam Imm, Abraham Wandersman, and Maria E. Fernandez
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implementation science ,organizational readiness ,implementation strategies ,implementation mapping ,change management ,Public aspects of medicine ,RA1-1270 - Abstract
Organizational readiness is essential for high-quality implementation of innovations (programs, policies, practices, or processes). The R = MC2 heuristic describes three readiness components necessary for implementation—the general functioning of the organization (general capacities), the ability to deliver a particular innovation (innovation-specific capacities), and the motivation to implement the innovation. In this article, we describe how we used the Readiness Building System (RBS) for assessing, prioritizing, and improving readiness and Implementation Mapping (IM), a systematic process for planning implementation strategies, to build organizational readiness for implementation of sexual assault prevention evidence-based interventions (EBIs). While RBS provides an overarching approach for assessing and prioritizing readiness constructs (according to the R = MC2 heuristic; Readiness = Motivation x general Capacity × innovation specific Capacity), it does not provide specific guidance on the development and/or selection and tailoring of strategies to improve readiness. We used the five IM tasks to identify and prioritize specific readiness goals and develop readiness-building strategies to improve subcomponents described in the R = MC2 heuristic. This article illustrates how IM can be used synergistically with the RBS in applied contexts to plan implementation strategies that will improve organizational readiness and implementation outcomes. Specifically, we provide an example of using these two frameworks as part of the process of building organizational readiness for implementation of sexual assault prevention EBIs.
- Published
- 2022
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- View/download PDF
35. Field induced anisotropic cooperativity in a magnetic colloidal glass
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Wandersman, E, Chushkin, Y, Dubois, E, Dupuis, V, Robert, A, and Perzynski, R
- Subjects
Condensed Matter - Soft Condensed Matter - Abstract
The translational dynamics in a repulsive colloidal glass-former is probed by time-resolved X-ray Photon Correlation Spectroscopy. In this dense dispersion of charge-stabilized and magnetic nanoparticles, the interaction potential can be tuned, from quasi-isotropic to anisotropic by applying an external magnetic field. Structural and dynamical anisotropies are reported on interparticle lengthscales associated with highly anisotropic cooperativity, almost two orders of magnitude larger in the field direction than in the perpendicular direction and in zero field.
- Published
- 2015
36. Using Collaborative Coalition Processes to Advance Community Health, Well-Being, and Equity: A Multiple-Case Study Analysis from a National Community Transformation Initiative
- Author
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Reid, Amy, Abraczinskas, Michelle, Scott, Victoria, Stanzler, Morgen, Parry, Gareth, Scaccia, Jonathan, Wandersman, Abe, and Ramaswamy, Rohit
- Abstract
Spreading Community Accelerators Through Learning and Evaluation (SCALE) was a Robert Wood Johnson Foundation-funded initiative from 2015 to 2017 to build capability of 24 community coalitions to advance health, well-being, and equity. The SCALE theory of change had three components: develop leadership capability, build relationships within and between communities, and create an intercommunity system to spread promising ideas. The theory was operationalized through training academies, coaching, and peer-to-peer learning that explicitly addressed equity and systems change. In this article, we describe how SCALE facilitated community transformation related to Collaborating for Equity and Justice Principles 1, 3, 4, and 6. We conducted a multiple-case study approach with two community coalitions including site visits, interviews, and observation to illuminate underlying mechanisms of change by exploring how and why change occurs. Skid Row Women worked with women experiencing homelessness in Los Angeles to address diabetes and food systems. Healthy Livable Communities of Cattaraugus County used a portfolio of projects in order to create system changes to improve population health and increase access to services for people with disabilities in rural New York State. Through our analysis, we describe how two coalitions used SCALE tools for collaborative coalition processes such as aim setting, relationship building, and shared decision making with community residents. Our findings suggest that advancing Collaborating for Equity and Justice principles requires self-reflection and courage; new ways of being in relationship; learning from failure; productive conflict to explicitly address power, racism, and other forms of oppression; and methods to test systems improvement ideas.
- Published
- 2019
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37. Dissemination of Evidence-Based Prevention Interventions and Policies
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Chinman, Matthew, Acosta, Joie, Ebener, Patricia, Hunter, Sarah, Imm, Pamela, Wandersman, Abraham, Sloboda, Zili, Series Editor, Petras, Hanno, editor, Robertson, Elizabeth, editor, and Hingson, Ralph, editor
- Published
- 2019
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38. Development of a comprehensive measure of organizational readiness (motivation × capacity) for implementation: a study protocol
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Timothy J. Walker, Heather M. Brandt, Abraham Wandersman, Jonathan Scaccia, Andrea Lamont, Lauren Workman, Emanuelle Dias, Pamela M. Diamond, Derek W. Craig, and Maria E. Fernandez
- Subjects
Readiness ,R = MC 2 ,Interactive systems framework for dissemination and implementation ,Implementation measurement ,Colorectal cancer screening implementation ,Medicine (General) ,R5-920 - Abstract
Abstract Background Organizational readiness is important for the implementation of evidence-based interventions. Currently, there is a critical need for a comprehensive, valid, reliable, and pragmatic measure of organizational readiness that can be used throughout the implementation process. This study aims to develop a readiness measure that can be used to support implementation in two critical public health settings: federally qualified health centers (FQHCs) and schools. The measure is informed by the Interactive Systems Framework for Dissemination and Implementation and R = MC 2 heuristic (readiness = motivation × innovation-specific capacity × general capacity). The study aims are to adapt and further develop the readiness measure in FQHCs implementing evidence-based interventions for colorectal cancer screening, to test the validity and reliability of the developed readiness measure in FQHCs, and to adapt and assess the usability and validity of the readiness measure in schools implementing a nutrition-based program. Methods For aim 1, we will conduct a series of qualitative interviews to adapt the readiness measure for use in FQHCs. We will then distribute the readiness measure to a developmental sample of 100 health center sites (up to 10 staff members per site). We will use a multilevel factor analysis approach to refine the readiness measure. For aim 2, we will distribute the measure to a different sample of 100 health center sites. We will use multilevel confirmatory factor analysis models to examine the structural validity. We will also conduct tests for scale reliability, test-retest reliability, and inter-rater reliability. For aim 3, we will use a qualitative approach to adapt the measure for use in schools and conduct reliability and validity tests similar to what is described in aim 2. Discussion This study will rigorously develop a readiness measure that will be applicable across two settings: FQHCs and schools. Information gained from the readiness measure can inform planning and implementation efforts by identifying priority areas. These priority areas can inform the selection and tailoring of support strategies that can be used throughout the implementation process to further improve implementation efforts and, in turn, program effectiveness.
- Published
- 2020
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39. Development and pilot test of criteria defining best practices for organizational sexual assault prevention
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Joie Acosta, Matthew Chinman, Andra Tharp, Jack Baker, Paul Flaspohler, Beverly Fortson, Amy Kerr, Andrea Lamont, Amanda Meyer, Sierra Smucker, Katelyn Wargel, and Abraham Wandersman
- Subjects
Medicine - Abstract
Sexual violence affects millions of Americans, and approximately one out of every three women and one out of every four men have experienced sexual violence during their lifetime. While prevention efforts have focused on implementing specific programmatic approaches, there has been relatively little focus on developing comprehensive and effective approaches to reduce sexual assault prevention across an organization. This study describes the development of the Prevention Evaluation Framework, an assessment targeting organizational best practices for comprehensive sexual assault prevention across multiple domains including human resources, collaborative relationships and infrastructure, use of evidence-informed approaches, quality implementation and continuous evaluation of programs/policies. Using the structured RAND/University of California, Los Angeles appropriateness method to develop the assessment, we conducted a literature review and solicited expert feedback about what a comprehensive organizational approach to sexual assault prevention should entail. We then pilot tested the assessment with 3 United States military service academies; and continued to improve and adapt the assessment to a range of organizations with input from 6 Department of Defense headquarters organizations, and 9 universities across the country. Given the nascent state of the evidence about what makes an effective organizational approach to sexual assault prevention, the assessment reflects one way of promoting quality in this evolving field. The consistency between the experts’ ratings and the literature, and the relevance of the items across organizations suggest that the assessment provides important guidance to inform the development of comprehensive organizational approaches to sexual assault prevention and to the evaluation of ongoing efforts.
- Published
- 2022
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- View/download PDF
40. Probing locally the onset of slippage at a model multi-contact interface
- Author
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Romero, V., Wandersman, E., Debrégeas, G., and Prevost, A.
- Subjects
Condensed Matter - Soft Condensed Matter - Abstract
We report on the multi-contact frictional dynamics of model elastomer surfaces rubbed against bare glass slides. The surfaces consist of layers patterned with thousands spherical caps (radius of curvature 100 $\mu$m) distributed both spatially and in height, regularly or randomly. Use of spherical asperities yields circular micro-contacts whose radius is a direct measure of the contact pressure distribution. In addition, optical tracking of individual contacts provides the in-plane deformations of the tangentially loaded interface, yielding the shear force distribution. We then investigate the stick-slip frictional dynamics of a regular hexagonal array. For all stick phases including the initial one, slip precursors are evidenced. They are found to propagate quasi-statically, normally to the iso- pressure contours. A simple quasi-static model relying on the existence of interfacial stress gradients is derived and predicts qualitatively the position of slip precursors., Comment: 5 pages, 5 figures
- Published
- 2013
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41. Bulk modulus of the nanoparticle system in concentrated magnetic fluids and local field-induced structural anisotropy
- Author
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Wandersman, E., Cēbers, A., Dubois, E., Mériguet, G., Robert, A., and Perzynski, R.
- Subjects
Condensed Matter - Soft Condensed Matter ,Condensed Matter - Materials Science - Abstract
In the present study we probe the bulk modulus and the structure of concentrated magnetic fluids by Small Angle X-ray Scattering. The electrostatically stabilized nanoparticles experience a repulsive interparticle potential modulated by dipolar magnetic interactions. On the interparticle distance lengthscale, we show that nanoparticles are trapped under-field in oblate cages formed by their first neighbours. We propose a theoretical model of magnetostriction for the field-induced deformation of the cage. This model captures the anisotropic features of the experimentally observed scattering pattern on the local scale in these strongly interacting colloidal dispersions., Comment: 12 pages, 9 figures
- Published
- 2013
42. Nonlocal Granular Rheology: Role of Pressure and Anisotropy
- Author
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Wandersman, Elie and van Hecke, Martin
- Subjects
Condensed Matter - Soft Condensed Matter ,Condensed Matter - Materials Science - Abstract
We probe the secondary rheology of granular media, by imposing a main flow and immersing a vane-shaped probe into the slowly flowing granulate. The secondary rheology is then the relation between the exerted torque T and rotation rate \omega of our probe. In the absence of any main flow, the probe experiences a clear yield-stress, whereas for any finite flow rate, the yield stress disappears and the secondary rheology takes on the form of a double exponential relation between \omega and T. This secondary rheology does not only depend on the magnitude of T, but is anisotropic --- which we show by varying the relative orientation of the probe and main flow. By studying the depth dependence of the three characteristic torques that characterize the secondary rheology, we show that for counter flow, the dominant contribution is frictional like --- i.e., T and pressure are proportional for given \omega --- whereas for co flow, the situation is more complex. Our experiments thus reveal the crucial role of anisotropy for the rheology of granular media., Comment: 6 pages, 5 figures
- Published
- 2013
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43. Adhesion Percolation Determines Global Deformation Behavior in Biomimetic Emulsions
- Author
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Lorraine Montel, Iaroslava Golovkova, Silvia Grigolon, Elie Wandersman, Alexis M. Prevost, Thibault Bertrand, and Lea-Laetitia Pontani
- Subjects
viscoelasticity ,biomimetic emulsions ,adhesion ,biological tissues ,deformation ,percolation ,Physics ,QC1-999 - Abstract
Characterizing the mechanical properties of tissues is key for the understanding of fundamental biological processes such as morphogenesis or tumor progression. In particular, the intercellular adhesion forces, mediated by transmembrane proteins like cadherins, are expected to control the topology and viscoelastic behavior of tissues under mechanical stress. In order to understand the influence of adhesion in tissues, we use biomimetic emulsions in which droplets mimic cells and adhere to each other through specific bonds. Here, we tune both the binding energy of the adhesive inter-droplets contacts as well as the fraction of contacts that are adhesive, thereby defining a so-called adhesiveness. Our experimental results show that adhesion prevents the emergence of local order in emulsions even at high packing fractions by preventing energetically costly droplet rearrangements. By studying the deformation of droplets within packings with different average adhesiveness values, we reveal the existence of a threshold value of adhesiveness above which all droplets in a packing are deformed as adhesive ones irrespective of their local adhesive properties. We show that this critical adhesiveness coincides with the threshold for percolation of adhesive structures throughout the tissue. From a biological point of view, this indicates that only a fraction of adhesive cells would be sufficient to tune the global mechanical properties of a tissue, which would be critical during processes such as morphogenesis.
- Published
- 2021
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44. Innovative Methods in Evaluation: An Application of Latent Class Analysis to Assess How Teachers Adopt Educational Innovations
- Author
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Lamont, Andrea E., Markle, Robert S., Wright, Annie, Abraczinskas, Michelle, Siddall, James, Wandersman, Abraham, Imm, Pam, and Cook, Brittany
- Abstract
Traditional methods of evaluation are limited in their ability to answer key questions often of interest to process evaluators, such as heterogeneity in the ways individuals adopt new programs. In this article, we demonstrate how a statistical approach, Latent Class Analysis, can help improve the quality of process evaluations and illustrate its use in an evaluation of an educational technology integration program in a large school district. In this illustration, we were interested in detecting variability in the ways teachers adopted the new program. We defined classes based on a set of innovative teaching strategies associated with educational technology. Results showed five distinct subgroups of teachers, based on level of program adoption. Results also demonstrate that specific school support strategies (professional development and personalized computing devices) facilitated program adoption. These findings can help to inform individualized support for teachers to optimize the ease and quality with which they are able to adopt new skills in the classroom.
- Published
- 2018
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45. Rheology of sedimenting particle pastes
- Author
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Fall, Abdoulaye, de Cagny, Henri, Bonn, Daniel, Ovarlez, Guillaume, Wandersman, Elie, Dijksman, Joshua A., and van Hecke, Martin
- Subjects
Condensed Matter - Soft Condensed Matter - Abstract
We study the local and global rheology of non-Brownian suspensions in a solvent that is not density-matched, leading to either creaming or sedimentation of the particles. Both local and global measurements show that the incomplete density matching leads to the appearance of a critical shear rate above which the suspension is homogenized by the flow, and below which sedimentation or creaming happens. We show that the value of the critical shear rate and its dependence on the experimental parameters are governed by a simple competition between the viscous and gravitational forces, and present a simple scaling model that agrees with the experimental results from different types of experiments (local and global) in different setups and systems.
- Published
- 2012
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- View/download PDF
46. Particle Diffusion in Slow Granular Bulk Flows
- Author
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Wandersman, Elie, Dijksman, Joshua A., and van Hecke, Martin
- Subjects
Condensed Matter - Soft Condensed Matter ,Condensed Matter - Materials Science ,Condensed Matter - Statistical Mechanics - Abstract
We probe the diffusive motion of particles in slowly sheared three dimensional granular suspensions. For sufficiently large strains, the particle dynamics exhibits diffusive Gaussian statistics, with the diffusivity proportional to the local strain rate - consistent with a local, quasi static picture. Surprisingly, the diffusivity is also inversely proportional to the depth of the particles within the flow - at the free surface, diffusivity is thus ill defined. We find that the crossover to Gaussian displacement statistics is governed by the same depth dependence, evidencing a non-trivial strain scale in three dimensional granular flows., Comment: 6 pages
- Published
- 2012
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47. Texture-induced modulations of friction force: the fingerprint effect
- Author
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Wandersman, E., Candelier, R., Debregeas, G., and Prevost, Alexis
- Subjects
Condensed Matter - Soft Condensed Matter - Abstract
Dry solid friction is often accompanied by force modulations originating from stick-slip instabilities. Here a distinct, quasi-static mechanism is evidenced leading to quasi-periodic force oscillations during sliding contact between an elastomer block, whose surface is patterned with parallel grooves, and finely abraded glass slides. The dominant oscillation frequency is set by the ratio between the sliding velocity and the period of the grooves. A mechanical model is proposed that provides a quantitative prediction for the amplitude of the force modulations as a function of the normal load, the period of the grooves and the roughness characteristics of the substrate. The model's main ingredient is the non-linearity of the friction law. Since such non-linearity is ubiquitous for soft solids, this "fingerprint effect" should be relevant to a large class of frictional configurations and might in particular have important consequences in human (or humanoid) active digital touch., Comment: 4 pages
- Published
- 2011
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48. From Frictional to Viscous Behavior: Three Dimensional Imaging and Rheology of Gravitational Suspensions
- Author
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Dijksman, Joshua A., Wandersman, Elie, Slotterback, Steven, Berardi, Christian R., Updegraff, William Derek, van Hecke, Martin, and Losert, Wolfgang
- Subjects
Condensed Matter - Soft Condensed Matter - Abstract
We probe the three dimensional flow structure and rheology of gravitational (non-density matched) suspensions for a range of driving rates in a split-bottom geometry. We establish that for sufficiently slow flows, the suspension flows as if it were a dry granular medium, and confirm recent theoretical modeling on the rheology of split-bottom flows. For faster driving, the flow behavior is shown to be consistent with the rheological behavior predicted by the recently developed "inertial number approaches for suspension flows., Comment: 5 pages, 4 figures, accepted for Phys. Rev. E. (R)
- Published
- 2010
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49. Buckled in translation
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Wandersman, E., Quennouz, N., Fermigier, M., Lindner, A., and Roure, O. du
- Subjects
Condensed Matter - Soft Condensed Matter ,Condensed Matter - Materials Science ,Physics - Fluid Dynamics - Abstract
We report experiments on the deformation and transport of an elastic fiber in a viscous cellular flow, namely a lattice of counter-rotative vortices. We show that the fiber can buckle when approaching a stagnation point. By tuning either the flow or fiber properties, we measure the onset of this buckling instability. The buckling threshold is determined by the relative intensity of viscous and elastic forces, the elasto-viscous number Sp. Moreover we show that flexible fibers escape faster from a vortex (formed by closed streamlines) compared to rigid fibers. As a consequence, the deformation of the fiber changes its transport properties in the cellular flow., Comment: 5 pages, 4 figures
- Published
- 2010
50. Flow-induced Agitations Create a Granular Fluid
- Author
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Nichol, Kiri, Zanin, Alexey, Bastien, Renaud, Wandersman, Elie, and van Hecke, Martin
- Subjects
Condensed Matter - Other Condensed Matter ,Condensed Matter - Soft Condensed Matter - Abstract
We fluidize a granular medium through localized stirring and probe the mechanical response of quiescent regions far away from the main flow. In these regions the material behaves like a liquid: high-density probes sink, low-density probes float at the depth given by Archimedes' law, and drag forces on moving probes scale linearly with the velocity. The fluid-like character of the material is set by agitations generated in the stirred region, suggesting a non-local rheology: the relation between applied stress and observed strain rate in one location depends on the strain rate in another location.
- Published
- 2009
- Full Text
- View/download PDF
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