Phase Transitions and Adsorption Isotherm in Multilayer Adsorbates with Lateral Interactions

We analyze here a model for an adsorbate system composed of many layers by extending a theoretical approach used to describe pattern formation on a monolayer of adsorbates with lateral interactions. The approach shows, in addition to a first order phase transition in the first layer, a transition in the second layer together with evidence of a "cascade" of transitions if more layers are included. The transition profiles, showing a staircase structure, corroborate this picture. The adsorption isotherm that came out of this approach is in qualitative agreement with numerical and experimental results.Comment: Submited to Physica A, LaTex, 22 pgs, 6 figure

Evaluation of two thermal neutron detection units consisting of ZnS/6{}^6LiF scintillating layers with embedded WLS fibers read out with a SiPM

Two single channel detection units for thermal neutron detection are investigated in a neutron beam. They consist of two ZnS/${}^6$LiF scintillating layers sandwiching an array of WLS fibers. The pattern of this units can be repeated laterally and vertically in order to build up a one dimensional position sensitive multi-channel detector with the needed sensitive surface and with the required neutron absorption probability. The originality of this work arises from the fact that the WLS fibers are read out with SiPMs instead of the traditionally used PMTs or MaPMTs. The signal processing system is based on a photon counting approach. For SiPMs with a dark count rate as high as 0.7 MHz, a trigger efficiency of 80% is achieved together with a system background rate lower than ${10}^{-3}$ Hz and a dead time of 30 $\mu$s. No change of performance is observed for neutron count rates of up to 3.6 kHz.Comment: Submitted to Nuclear Instruments and Methods

Re-examining teacher candidate performance on world language edTPA as a consequential assessment

Used by almost 800 educator preparation programs in more than 40 states and the District of Columbia, edTPA seeks to measure content-specific outcomes of beginning teachers as a high-stakes assessment. Many states also use edTPA to inform teacher licensure or certification decisions, making the assessment consequential for individual teacher candidates. The present study focuses on teacher candidates’ performance on the World Language edTPA, targeting two world language teacher education programs since the assessment became consequential for licensure in their respective states. It then compares findings to those of a previous study of the same programs’ World Language edTPA performance (Hildebrandt & Swanson, 2014) from before the assessment became consequential for teacher licensure decisions in 2015 in [State X] and [State Y]. Programmatic changes were implemented after initial inspection of the data and results from such curricular changes are discussed in terms of local impact. Additionally, national trends are identified and discussed. Findings demonstrate serious issues regarding this assessment of beginning teacher effectiveness as related to World Language teaching and learning. This research has implications for teacher preparation programs and other educational stakeholders alike

World Language Teacher Candidate Performance on edTPA: An Exploratory Study

Federal and state legislation continues to promote teacher accountability in the United States. The new edTPA, a subject-specific teacher performance assessment, is purported to measure beginning teacher readiness and is being pilot tested and implemented for licensure and certification decisions across the country. In this exploratory quantitative study, the researchers examined edTPA scores of 21 world language teacher candidates from two teacher preparation programs and compared those results to the cut scores for the states of Washington and New York. Results indicated that participants performed best in the planning section and were most challenged by the assessment section. This research has implications for teacher certification candidates, world language teacher preparation programs, policy makers, and other stakeholders

Monte Carlo simulations of fluid vesicles with in plane orientational ordering

We present a method for simulating fluid vesicles with in-plane orientational ordering. The method involves computation of local curvature tensor and parallel transport of the orientational field on a randomly triangulated surface. It is shown that the model reproduces the known equilibrium conformation of fluid membranes and work well for a large range of bending rigidities. Introduction of nematic ordering leads to stiffening of the membrane. Nematic ordering can also result in anisotropic rigidity on the surface leading to formation of membrane tubes.Comment: 11 Pages, 12 Figures, To appear in Phys. Rev.