1,432 research outputs found
Learning Style Diversity in Post –Secondary Distance Education
During the fall semester of 2005, 153 university graduate students’ preferred learning styles were measured with the Kolb Learning Style Inventory, online version 3.1. The primary findings of the study indicated all of the learning styles and processes described by Kolb were represented in the distance learning population and suggested distance and residential learners uniquely engage the learning process. Biblical references were discussed with respect to the uniqueness displayed by study participants
Assessing molecular simulation for the analysis of lipid monolayer reflectometry
Using molecular simulation to aid in the analysis of neutron reflectometry
measurements is commonplace. However, reflectometry is a tool to probe
large-scale structures, and therefore the use of all-atom simulation may be
irrelevant. This work presents the first direct comparison between the
reflectometry profiles obtained from different all-atom and coarse-grained
molecular dynamics simulations. These are compared with a traditional model
layer structure analysis method to determine the minimum simulation resolution
required to accurately reproduce experimental data. We find that systematic
limits reduce the efficacy of the MARTINI potential model, while the Berger
united-atom and Slipids all-atom potential models agree similarly well with the
experimental data. The model layer structure gives the best agreement, however,
the higher resolution simulation-dependent methods produce an agreement that is
comparable. Finally, we use the atomistic simulation to advise on possible
improvements that may be offered to the model layer structures, creating a more
realistic monolayer model.Comment: Electronic Supplementary Information (ESI) available: All
analysis/plotting scripts and figure files, allowing for a fully
reproducible, and automated, analysis workflow for the work presented is
available at \url{https://github.com/arm61/sim_vs_trad} (DOI:
10.5281/zenodo.2600729) under a CC BY-SA 4.0 licens
An introduction to classical molecular dynamics simulation for experimental scattering users
Classical molecular dynamics simulations are a common component of
multi-modal analyses from scattering measurements, such as small-angle
scattering and diffraction. Users of these experimental techniques often have
no formal training in the theory and practice of molecular dynamics simulation,
leading to the possibility of these simulations being treated as a "black box"
analysis technique. In this article, we describe an open educational resource
(OER) designed to introduce classical molecular dynamics to users of scattering
methods. This resource is available as a series of interactive web pages, which
can be easily accessed by students, and as an open source software repository,
which can be freely copied, modified, and redistributed by educators. The topic
covered in this OER includes classical atomistic modelling, parameterising
interatomic potentials, molecular dynamics simulations, typical sources of
error, and some of the approaches to using simulations in the analysis of
scattering data.Comment: Electronic Supplementary Information (ESI) available: All
analysis/plotting scripts and figure files, allowing for a fully
reproducible, and automated, analysis workflow for the work presented is
available at \url{https://github.com/arm61/sim_and_scat_paper} (DOI:
10.5281/zenodo.2556826) under a CC BY-SA 4.0 licens
Huygens' Principle for the Klein-Gordon equation in the de Sitter spacetime
In this article we prove that the Klein-Gordon equation in the de Sitter
spacetime obeys the Huygens' principle only if the physical mass of the
scalar field and the dimension of the spatial variable are tied by
the equation . Moreover, we define the incomplete Huygens'
principle, which is the Huygens' principle restricted to the vanishing second
initial datum, and then reveal that the massless scalar field in the de Sitter
spacetime obeys the incomplete Huygens' principle and does not obey the
Huygens' principle, for the dimensions , only. Thus, in the de Sitter
spacetime the existence of two different scalar fields (in fact, with m=0 and
), which obey incomplete Huygens' principle, is equivalent to
the condition (in fact, the spatial dimension of the physical world). For
these two values of the mass are the endpoints of the so-called in
quantum field theory the Higuchi bound. The value of the
physical mass allows us also to obtain complete asymptotic expansion of the
solution for the large time. Keywords: Huygens' Principle; Klein-Gordon
Equation; de Sitter spacetime; Higuchi Boun
pylj: A teaching tool for classical simulation
pylj is an educational software to introduce students to classical atomistic simulation usinga Lennnard-Jones potential model (Jones 1924). pylj is written in Python (using Cythonfor pairwise interactions) and uses Jupyter notebooks (Kluyver et al. 2016) and Matplotlib (Hunter 2007) for visualisation (see example below). It can be easily deployed in acomputer laboratory, and students interact with it without needing to use the commandline, as would be the case for other molecular dynamics packages like Gromacs(Berendsen,Spoel, and Drunen 1995), LAMMPS (Plimpton 1995), or DLPOLY (Smith, Yong, andRodger 2002). We provide example notebooks in the repository, showing how to use pyljto simulate a 2D gas system using either m
Recommended from our members
Inhibition of chemotherapy resistant breast cancer stem cells by a ROR1 specific antibody.
Breast cancers enduring treatment with chemotherapy may be enriched for cancer stem cells or tumor-initiating cells, which have an enhanced capacity for self-renewal, tumor initiation, and/or metastasis. Breast cancer cells that express the type I tyrosine kinaselike orphan receptor ROR1 also may have such features. Here we find that the expression of ROR1 increased in breast cancer cells following treatment with chemotherapy, which also enhanced expression of genes induced by the activation of Rho-GTPases, Hippo-YAP/TAZ, or B lymphoma Mo-MLV insertion region 1 homolog (BMI1). Expression of ROR1 also enhanced the capacity of breast cancer cells to invade Matrigel, form spheroids, engraft in Rag2-/-[Formula: see text] mice, or survive treatment with paclitaxel. Treatment of mice bearing breast cancer patient-derived xenografts (PDXs) with the humanized anti-ROR1 monoclonal antibody cirmtuzumab repressed expression of genes associated with breast cancer stemness, reduced activation of Rho-GTPases, Hippo-YAP/TAZ, or BMI1, and impaired the capacity of breast cancer PDXs to metastasize or reengraft Rag2-/-[Formula: see text] mice. Finally, treatment of PDX-bearing mice with cirmtuzumab and paclitaxel was more effective than treatment with either alone in eradicating breast cancer PDXs. These results indicate that targeting ROR1 may improve the response to chemotherapy of patients with breast cancer
Plasma anandamide concentrations are lower in children with autism spectrum disorder
Background: Autism spectrum disorder (ASD) is a neurodevelopmentaldisorder characterized by restricted, stereotyped behaviors and impairments in social communication. Although the underlying biological mechanisms of ASD remain poorly understood, recent preclinical research has implicated the endogenous cannabinoid (or endocannabinoid), anandamide, as a significant neuromodulator in rodent models of ASD. Despite this promising preclinical evidence, no clinical studies to date have tested whether endocannabinoids are dysregulated in individuals with ASD. Here, we addressed this critical gap in knowledge by optimizing liquid chromatography-tandem mass spectrometry methodology to quantitatively analyze anandamide concentrations in banked blood samples collected from a cohort of children withand without ASD (N= 112). Findings: Anandamide concentrations significantly differentiated ASD cases (N= 59) from controls (N= 53), such that children with lower anandamide concentrations were more likely to have ASD (p= 0.041). In keeping with this notion, anandamide concentrations were also significantly lower in ASD compared to control children (p= 0.034). Conclusions: These findings are the first empirical human data to translate preclinical rodent findings to confirm a link between plasma anandamide concentrations in children with ASD. Although preliminary, these data suggest that impaired anandamide signaling may be involved in the pathophysiology of ASD
The nuclear structural protein NuMA is a negative regulator of 53BP1 in DNA double-strand break repair
P53-binding protein 1 (53BP1) mediates DNA repair pathway choice and promotes checkpoint activation. Chromatin marks induced by DNA double-strand breaks and recognized by 53BP1 enable focal accumulation of this multifunctional repair factor at damaged chromatin. Here, we unveil an additional level of regulation of 53BP1 outside repair foci. 53BP1 movements are constrained throughout the nucleoplasm and increase in response to DNA damage. 53BP1 interacts with the structural protein NuMA, which controls 53BP1 diffusion. This interaction, and colocalization between the two proteins in vitro and in breast tissues, is reduced after DNA damage. In cell lines and breast carcinoma NuMA prevents 53BP1 accumulation at DNA breaks, and high NuMA expression predicts better patient outcomes. Manipulating NuMA expression alters PARP inhibitor sensitivity of BRCA1-null cells, end-joining activity, and immunoglobulin class switching that rely on 53BP1. We propose a mechanism involving the sequestration of 53BP1 by NuMA in the absence of DNA damage. Such a mechanism may have evolved to disable repair functions and may be a decisive factor for tumor responses to genotoxic treatments
Pointing all around you : selection performance of mouse and ray-cast pointing in full-coverage displays
Funding: SurfNet (NSERC, Canada), EPSRC (Small Equipment Grant).As display environments become larger and more diverse - now often encompassing multiple walls and room surfaces - it is becoming more common that users must find and manipulate digital artifacts not directly in front of them. There is little understanding, however, about what techniques and devices are best for carrying out basic operations above, behind, or to the side of the user. We conducted an empirical study comparing two main techniques that are suitable for full-coverage display environments: mouse-based pointing, and ray-cast `laser' pointing. Participants completed search and pointing tasks on the walls and ceiling, and we measured completion time, path lengths and perceived effort. Our study showed a strong interaction between performance and target location: when the target position was not known a priori the mouse was fastest for targets on the front wall, but ray-casting was faster for targets behind the user. Our findings provide new empirical evidence that can help designers choose pointing techniques for full-coverage spaces.Postprin
- …