2,348 research outputs found
An epistemology and expectations survey about experimental physics: Development and initial results
In response to national calls to better align physics laboratory courses with
the way physicists engage in research, we have developed an epistemology and
expectations survey to assess how students perceive the nature of physics
experiments in the contexts of laboratory courses and the professional research
laboratory. The Colorado Learning Attitudes about Science Survey for
Experimental Physics (E-CLASS) evaluates students' epistemology at the
beginning and end of a semester. Students respond to paired questions about how
they personally perceive doing experiments in laboratory courses and how they
perceive an experimental physicist might respond regarding their research.
Also, at the end of the semester, the E-CLASS assesses a third dimension of
laboratory instruction, students' reflections on their course's expectations
for earning a good grade. By basing survey statements on widely embraced
learning goals and common critiques of teaching labs, the E-CLASS serves as an
assessment tool for lab courses across the undergraduate curriculum and as a
tool for physics education research. We present the development, evidence of
validation, and initial formative assessment results from a sample that
includes 45 classes at 20 institutions. We also discuss feedback from
instructors and reflect on the challenges of large-scale online administration
and distribution of results.Comment: 31 pages, 9 figures, 3 tables, submitted to Phys. Rev. - PE
Development and results from a survey on students views of experiments in lab classes and research
The Colorado Learning Attitudes about Science Survey for Experimental Physics
(E-CLASS) was developed as a broadly applicable assessment tool for
undergraduate physics lab courses. At the beginning and end of the semester,
the E-CLASS assesses students views about their strategies, habits of mind, and
attitudes when doing experiments in lab classes. Students also reflect on how
those same strategies, habits-of-mind, and attitudes are practiced by
professional researchers. Finally, at the end of the semester, students reflect
on how their own course valued those practices in terms of earning a good
grade. In response to frequent calls to transform laboratory curricula to more
closely align it with the skills and abilities needed for professional
research, the E-CLASS is a tool to assess students' perceptions of the gap
between classroom laboratory instruction and professional research. The E-CLASS
has been validated and administered in all levels of undergraduate physics
classes. To aid in its use as a formative assessment tool, E-CLASS provides all
participating instructors with a detailed feedback report. Example figures and
analysis from the report are presented to demonstrate the capabilities of the
E-CLASS. The E-CLASS is actively administered through an online interface and
all interested instructors are invited to administer the E-CLASS their own
classes and will be provided with a summary of results at the end of the
semester
The Effects of Modifying the Formality Level of ESL Composition Questions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90194/1/3586551.pd
Essential Microenvironment for Thymopoiesis is Preserved in Human Adult and Aged Thymus
Normal human thymuses at various ages were immunohistologically examined in order to determine whether adult or aged thymus maintained the microenvironment for the T cell development and thymopoiesis was really ongoing. To analyze the thymic microenvironment, two monoclonal antibodies (MoAb) were employed. One is MoAb to IL-1 receptor (IL-1R) recognizing medullary and subcapsular cortical epithelial cells of normal infant human thymus. The other is UH-1 MoAb recognizing thymic epithelial cells within the cortex, which are negative with IL-1R-MoAb. Thymus of subjects over 20 years of age was split into many fragments and dispersed in the fatty tissue. However, the microenvironment of each fragment was composed of both IL-1R positive and UH-1 positive epithelial cells, and the UH-1 positive portion was populated with lymphocytes showing a follicle-like appearance. Lymphocytes in these follicle-like portions were mostly CD4+CD8+ double positive cells and contained many proliferating cells as well as apoptotic cells. Thus these follicle-like portions in adult and aged thymus were considered to be functioning as cortex as in infant thymus. Proliferative activity of thymocytes in the thymic cortex and the follicle-like portions definitely declined with advance of age, while incidence of apoptotic thymocytes increased with aging
Dissecting neural pathways for forgetting in Drosophila olfactory aversive memory
Recent studies have identified molecular pathways driving forgetting and supported the notion that forgetting is a biologically active process. The circuit mechanisms of forgetting, however, remain largely unknown. Here we report two sets of Drosophila neurons that account for the rapid forgetting of early olfactory aversive memory. We show that inactivating these neurons inhibits memory decay without altering learning, whereas activating them promotes forgetting. These neurons, including a cluster of dopaminergic neurons (PAM-beta'1) and a pair of glutamatergic neurons (MBON-gamma4>gamma1gamma2), terminate in distinct subdomains in the mushroom body and represent parallel neural pathways for regulating forgetting. Interestingly, although activity of these neurons is required for memory decay over time, they are not required for acute forgetting during reversal learning. Our results thus not only establish the presence of multiple neural pathways for forgetting in Drosophila but also suggest the existence of diverse circuit mechanisms of forgetting in different contexts
Guardians Ad Litem as Surrogate Parents: Implication for Role Definition and Confidentiality
SALMON (Scalable Ab-initio LightâMattersimulator for Optics and Nanoscience, http://salmon-tddft.jp) is a software package for the simulation of electron dynamics and optical properties of molecules, nanostructures, and crystalline solids based on first-principles time-dependent density functional theory. The core part of the software is the real-time, real-space calculation of the electron dynamics induced in molecules and solids by an external electric field solving the time-dependent KohnâSham equation. Using a weak instantaneous perturbing field, linear response properties such as polarizabilities and photoabsorptions in isolated systems and dielectric functions in periodic systems are determined. Using an optical laser pulse, the ultrafast electronic response that may be highly nonlinear in the field strength is investigated in time domain. The propagation of the laser pulse in bulk solids and thin films can also be included in the simulation via coupling the electron dynamics in many microscopic unit cells using Maxwellâs equations describing the time evolution of the electromagnetic fields. The code is efficiently parallelized so that it may describe the electron dynamics in large systems including up to a few thousand atoms. The present paper provides an overview of the capabilities of the software package showing several sample calculations. Program summary Program Title: SALMON: Scalable Ab-initio LightâMatter simulator for Optics and Nanoscience Program Files doi:http://dx.doi.org/10.17632/8pm5znxtsb.1 Licensing provisions: Apache-2.0 Programming language: Fortran 2003 Nature of problem: Electron dynamics in molecules, nanostructures, and crystalline solids induced by an external electric field is calculated based on first-principles time-dependent density functional theory. Using a weak impulsive field, linear optical properties such as polarizabilities, photoabsorptions, and dielectric functions are extracted. Using an optical laser pulse, the ultrafast electronic response that may be highly nonlinear with respect to the exciting field strength is described as well. The propagation of the laser pulse in bulk solids and thin films is considered by coupling the electron dynamics in many microscopic unit cells using Maxwellâs equations describing the time evolution of the electromagnetic field. Solution method: Electron dynamics is calculated by solving the time-dependent KohnâSham equation in real time and real space. For this, the electronic orbitals are discretized on a uniform Cartesian grid in three dimensions. Norm-conserving pseudopotentials are used to account for the interactions between the valence electrons and the ionic cores. Grid spacings in real space and time, typically 0.02 nm and 1 as respectively, determine the spatial and temporal resolutions of the simulation results. In most calculations, the ground state is first calculated by solving the static KohnâSham equation, in order to prepare the initial conditions. The orbitals are evolved in time with an explicit integration algorithm such as a truncated Taylor expansion of the evolution operator, together with a predictorâcorrector step when necessary. For the propagation of the laser pulse in a bulk solid, Maxwellâs equations are solved using a finite-difference scheme. By this, the electric field of the laser pulse and the electron dynamics in many microscopic unit cells of the crystalline solid are coupled in a multiscale framework
Self-organized density patterns of molecular motors in arrays of cytoskeletal filaments
The stationary states of systems with many molecular motors are studied
theoretically for uniaxial and centered (aster-like) arrangements of
cytoskeletal filaments using Monte Carlo simulations and a two-state model.
Mutual exclusion of motors from binding sites of the filaments is taken into
account. For small overall motor concentration, the density profiles are
exponential and algebraic in uniaxial and centered filament systems,
respectively. For uniaxial systems, exclusion leads to the coexistence of
regions of high and low densities of bound motors corresponding to motor
traffic jams, which grow upon increasing the overall motor concentration. These
jams are insensitive to the motor behavior at the end of the filament. In
centered systems, traffic jams remain small and an increase in the motor
concentration leads to a flattening of the profile, if the motors move inwards,
and to the build-up of a concentration maximum in the center of the aster if
motors move outwards. In addition to motors density patterns, we also determine
the corresponding patterns of the motor current.Comment: 48 pages, 8 figure
Absence of Ground States for a Class of Translation Invariant Models of Non-relativistic QED
We consider a class of translation invariant models of non-relativistic QED
with net charge. Under certain natural assumptions we prove that ground states
do not exist in the Fock space
Dicke-Type Energy Level Crossings in Cavity-Induced Atom Cooling: Another Superradiant Cooling
This paper is devoted to energy-spectral analysis for the system of a
two-level atom coupled with photons in a cavity. It is shown that the
Dicke-type energy level crossings take place when the atom-cavity interaction
of the system undergoes changes between the weak coupling regime and the strong
one. Using the phenomenon of the crossings we develop the idea of
cavity-induced atom cooling proposed by the group of Ritsch, and we lay
mathematical foundations of a possible mechanism for another superradiant
cooling in addition to that proposed by Domokos and Ritsch. The process of our
superradiant cooling can function well by cavity decay and by control of the
position of the atom, at least in (mathematical) theory, even if there is
neither atomic absorption nor atomic emission of photons.Comment: 15 pages; 8 figure
Critical Peaks Redefined - ΊâΚ=â€
6th International Workshop on Confluence6th International Workshop on ConfluenceLet a cluster be a term with a number of patterns occurring in it. We give two accounts of clusters, a geometric one as sets of (node and edge) positions, and an inductive one as pairs of terms with gaps (2nd order variables) and pattern-substitutions for the gaps. We show both notions of cluster and the corresponding refinement/coarsening orders on them, to be isomorphic. This equips clusters with a lattice structure which we lift to (parallel/multi) steps to yield an alternative account of the notion of critical peak
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