Scattering fingerprints of two-state dynamics

Particle transport in complex environments such as the interior of living cells is often (transiently) non-Fickian or anomalous, that is, it deviates from the laws of Brownian motion. Such anomalies may be the result of small-scale spatio-temporal heterogeneities in, or viscoelastic properties of, the medium, molecular crowding, etc. Often the observed dynamics displays multi-state characteristics, i.e. distinct modes of transport dynamically interconverting between each other in a stochastic manner. Reliably distinguishing between single- and multi-state dynamics is challenging and requires a combination of distinct approaches. To complement the existing methods relying on the analysis of the particle's mean squared displacement, position- or displacement-autocorrelation function, and propagators, we here focus on 'scattering fingerprints' of multi-state dynamics. We develop a theoretical framework for two-state scattering signatures—the intermediate scattering function and dynamic structure factor—and apply it to the analysis of simple model systems as well as particle-tracking experiments in living cells. We consider inert tracer-particle motion as well as systems with an internal structure and dynamics. Our results may generally be relevant for the interpretation of state-of-the-art differential dynamic microscopy experiments on complex particulate systems, as well as inelastic or quasielastic neutron (incl. spin-echo) and x-ray scattering probing structural and dynamical properties of macromolecules, when the underlying dynamics displays two-state transport

A Model for a Structured Clinical Development Program for First-Year Residents: Utilizing the Entrance OSCE, Individualized Learning Plans (ILPs), and Peer Clinical Coaching

Identification of incoming residents’ unique strengths and weaknesses in a clinical setting is important for developing an individualized educational curriculum and ultimately addressing specific needs. This resource presents and describes materials for a clinical development program for first year residents. The program is structured around three educational elements: an entrance Objective Structured Clinical Examination (OSCE), Individualized Learning Plan (ILP), and peer clinical coaching. The included files, which describe these three elements, are intended to serve as a resource for residency directors and/or graduate medical education faculty interested in constructing a similar program. In the described clinical development program, first-year Obstetrics and Gynecology residents participated in an entrance OSCE as a component of their orientation to residency. Their performance was evaluated through Faculty and Self-assessment tools and scored on a nine-point scale in accordance with the ACGME core competency scoring evaluation system. These evaluations were utilized in the creation of ILPs. Stated goals were translated into discrete learning objectives and then developed further through a learning strategy and timeline using the SMART model. As a component of a research study, first-year residents were randomized into one of two groups: clinical coaching group or individual implementation group. Senior resident volunteers served as peer clinical coaches after participating in a two-hour interactive workshop. The peer clinical coaches met with first-year residents on a monthly basis for four months to develop the resident’s ILP. Exit questionnaires were completed at the conclusion of the year-long program. The OSCE is a well-utilized tool to ensure direct observation, evaluate clinical performance in a simulated environment, and provide timely feedback. Another potential application of the OSCE is to provide a baseline evaluation of clinical performance that may be utilized in determining a starting point for clinical competencies. Utilizing the feedback from the OSCE to create an ILP may translate valuable feedback into measurable objectives and competencies, while also providing a model for reassessment and follow up. While the OSCE and the faculty mentored ILP have been well characterized in the literature, the concept of clinical coaching is relatively novel to medicine. Teaching and coaching differ in that teachers disseminate knowledge whereas coaches ensure performance. Seeking to elaborate on this relatively novel paradigm, we sought to characterize how resident’s global clinical experience was affected within this working model. Despite time constraints, both first-year residents and peer clinical coaches reported that clinical coaching improved their clinical experience. A structured clinical program incorporating an entrance OSCE, ILP, and peer clinical coaching holds promise in documentation of milestones and promoting life-long learning. AAMC MedEdPORTAL publication ID 10084. Link to original

Cold Reactions of Alkali and Water Clusters inside Helium Nanodroplets

The reaction of alkali (Na, Cs) clusters with water clusters embedded in helium nanodroplets is studied using femtosecond photo-ionization as well as electron impact ionization. Unlike Na clusters, Cs clusters are found to completely react with water in spite of the ultracold helium droplet environment. Mass spectra of the Cs$_n$+(H$_2$O)$_m$ reaction products are interpreted in terms of stability with respect to fragmentation using high-level molecular structure calculations

Chiral sedimentation of extended objects in viscous media

We study theoretically the chirality of a generic rigid object's sedimentation in a fluid under gravity in the low Reynolds number regime. We represent the object as a collection of small Stokes spheres or stokeslets, and the gravitational force as a constant point force applied at an arbitrary point of the object. For a generic configuration of stokeslets and forcing point, the motion takes a simple form in the nearly free draining limit where the stokeslet radius is arbitrarily small. In this case, the internal hydrodynamic interactions between stokeslets are weak, and the object follows a helical path while rotating at a constant angular velocity $\omega$ about a fixed axis. This $\omega$ is independent of initial orientation, and thus constitutes a chiral response for the object. Even though there can be no such chiral response in the absence of hydrodynamic interactions between the stokeslets, the angular velocity obtains a fixed, nonzero limit as the stokeslet radius approaches zero. We characterize empirically how $\omega$ depends on the placement of the stokeslets, concentrating on three-stokeslet objects with the external force applied far from the stokeslets. Objects with the largest $\omega$ are aligned along the forcing direction. In this case, the limiting $\omega$ varies as the inverse square of the minimum distance between stokeslets. We illustrate the prevalence of this robust chiral motion with experiments on small macroscopic objects of arbitrary shape.Comment: 35 pages, 10 figures; Section VII.A redone and other edits made for clarity. Accepted by Phys. Rev.

Marketing Ethics: A Study of Significance Within National Professional Associations

Professional associations are expected to maintain a reasonable standard of behavior regarding how they market to their service bases. Prior research indicates that the use of written marketing ethics is not standardized and that business codes of ethics are a potential base for a universal code of marketing ethics from which all professionals could draw. We use document analysis to review several professional associations’ codes of conduct across several industries and quantify the mention of marketing ethics within each code to identify and explore gaps. The review found that some associations’ codes had significant representation, and others had a minimal or nonexistent representation of marketing ethics. Our findings also indicate that several external forces may determine the presence of marketing ethics and that such sporadic inclusion of marketing ethics indicates a necessity to develop and implement marketing ethics to protect professional and organizational integrity and market and consumer interests