Colloids in light fields: particle dynamics in random and periodic energy landscapes

The dynamics of colloidal particles in potential energy landscapes have mainly been investigated theoretically. In contrast, here we discuss the experimental realization of potential energy landscapes with the help of light fields and the observation of the particle dynamics by video microscopy. The experimentally observed dynamics in periodic and random potentials are compared to simulation and theoretical results in terms of, e.g. the mean-squared displacement, the time-dependent diffusion coefficient or the non-Gaussian parameter. The dynamics are initially diffusive followed by intermediate subdiffusive behaviour which again becomes diffusive at long times. How pronounced and extended the different regimes are, depends on the specific conditions, in particular the shape of the potential as well as its roughness or amplitude but also the particle concentration. Here we focus on dilute systems, but the dynamics of interacting systems in external potentials, and thus the interplay between particle-particle and particle-potential interactions, is also mentioned briefly. Furthermore, the observed dynamics of dilute systems resemble the dynamics of concentrated systems close to their glass transition, with which it is compared. The effect of certain potential energy landscapes on the dynamics of individual particles appears similar to the effect of interparticle interactions in the absence of an external potential

Teaching & Learning The Spanish Aspect Using Blogs and Wikis: An Exploratory Study

This study investigated the influence of asynchronous computer text based technologies on the students’ performance when learning the preterite and the imperfect aspects in Spanish. Two research questions guided the study: Research Question 1) Is there a difference in students’ achievement levels in Spanish preterite and imperfect between those using wiki technologies and those using blog technologies after controlling for pre-intervention achievement levels? and Research Question 2) Are there differences in satisfaction levels for students learning Spanish preterite and imperfect via blog technologies as compared to those learning via wiki technologies? Results indicate that there were not significant differences between students who use blog or wiki technologies on performance levels when controlling for pre-existing knowledge. Results also indicated that there were not significant differences in satisfaction levels between those students using a wiki and those using a blog. These results suggest that wikis and blogs are good potential tools that may facilitate the teaching and learning of problematic grammar structures in a narrative context

Detection and identification of phytoplasmas in two vineyards located in a restricted geographic area in Italy

A survey to verify the presence of grapevine yellows was carried out in a restricted area of the Marche region (central east Italy) in a small geographic area. In two locations six grapevine varieties were examined and phytoplasmas belonging to four ribosomal groups were detected by PCR/RFLP analyses. The surveyed varieties were Passerina, Pecorino, Merlot, Sangiovese, Fedit and Montepulciano. The different phytoplasmas detected were present in a scattered manner in all the varieties, but only Passerina, Pecorino and Sangiovese where shown to be infected by “bois noir” (16SrXII-A) phytoplasmas. Considering the landscape shape and the age of the vineyards the source of BN infection and of the other phytoplasmas is very likely in the surrounding environment or vineyards

Casimir self-energy of a \delta-\delta' sphere

We extend previous work on the vacuum energy of a massless scalar field in the presence of singular potentials. We consider a single sphere denoted by the so-called "delta-delta prime" interaction. Contrary to the Dirac delta potential, we find a nontrivial one-parameter family of potentials such that the regularization procedure gives an unambiguous result for the Casimir self-energy. The procedure employed is based on the zeta function regularization and the cancellation of the heat kernel coefficient a_2. The results obtained are in agreement with particular cases, such as the Dirac delta or Robin and Dirichlet boundary conditions

Achieving 6th Magnet Designation via Virtual Visit during the COVID-19 Pandemic

Despite the challenges encountered with the arrival of the COVID-19 pandemic, Baptist Hospital of Miami achieved the prestigious American Nursing Credentialing Center Magnet 6th designation. We describe the journey including writing the documents, preparing for the virtual visit, and efforts from key stakeholders to support the virtual site visit with the use of technology, to hold videoconferencing and tours “on wheels.” Nurses showcased their professional practice and excellence in patient care through exemplars and narratives presented during the virtual visit. Last, we provide recommendations for success to organizations contemplating a virtual site visit