10,076 research outputs found
Designing, engineering, and testing wood structures
The objective of this paper is to introduce basic structural engineering concepts in a clear, simple manner while actively involving students. This project emphasizes the fact that a good design uses materials efficiently. The test structure in this experiment can easily be built and has various design options. Even when the structure is loaded to collapsing, only one or two pieces usually break, leaving the remaining pieces intact and reusable
In Synch but Not in Step: Circadian Clock Circuits Regulating Plasticity in Daily Rhythms
The suprachiasmatic nucleus (SCN) is a network of neural oscillators that program daily rhythms in mammalian behavior and physiology. Over the last decade much has been learned about how SCN clock neurons coordinate together in time and space to form a cohesive population. Despite this insight, much remains unknown about how SCN neurons communicate with one another to produce emergent properties of the network. Here we review the current understanding of communication among SCN clock cells and highlight a collection of formal assays where changes in SCN interactions provide for plasticity in the waveform of circadian rhythms in behavior. Future studies that pair analytical behavioral assays with modern neuroscience techniques have the potential to provide deeper insight into SCN circuit mechanisms
Recent Results on the Decay of Metastable Phases
We review some aspects of current knowledge regarding the decay of metastable
phases in many-particle systems. In particular we emphasize recent theoretical
and computational developments and numerical results regarding homogeneous
nucleation and growth in kinetic Ising and lattice-gas models. An introductory
discussion of the droplet theory of homogeneous nucleation is followed by a
discussion of Monte Carlo and transfer-matrix methods commonly used for
numerical study of metastable decay, including some new algorithms. Next we
discuss specific classes of systems. These include a brief discussion of recent
progress for fluids, and more exhaustive considerations of ferromagnetic Ising
models ({\it i.e.}, attractive lattice-gas models) with weak long-range
interactions and with short-range interactions. Whereas weak-long-range-force
(WLRF) models have infinitely long-lived metastable phases in the
infinite-range limit, metastable phases in short-range-force (SRF) models
eventually decay, albeit extremely slowly. Recent results on the finite-size
scaling of metastable lifetimes in SRF models are reviewed, and it is pointed
out that such effects may be experimentally observable.Comment: 34 pages, LaTex, 8 ps figs. on request, preprint FSU-SCRI-94-6
How young people from culturally and linguistically diverse backgrounds experience mental health: some insights for mental health nurses
This article reports on a part of a study which looked at the mental health of
culturally and linguistically diverse (CALD) young people. The research sought to learn
from CALD young people, carers, and service providers experiences relevant to the
mental health of this group of young people. The ultimate goal was to gain insights that
would inform government policy, service providers, ethnic communities and most
importantly the young people themselves. To this end, qualitative interviews were
undertaken with 123 CALD young people, 41 carers and 14 mental health service
providers in Queensland, Western Australia and South Australia.
Only one aspect of the study will be dealt with here, namely the views of the
young CALD participants, which included risk factors, coping strategies and
recommendations about how they could be supported in their struggle to maintain
mental health. One of the most important findings of the study relates to the resilience
of these young people and an insight into the strategies that they used to cope. The
efforts of these young people to assist us in our attempts to understand their situation
deserve to be rewarded by improvements in the care that we provide. To this end this
article sets out to inform mental health nurses of the results of the study so that they will
be in a position to better understand the needs and strengths of their CALD clients and
be in a better position to work effectively with them
English Literacy Development for English Language Learners: Does Spanish Instruction Promote or Hinder?
In this brief, the authors consider whether instruction in a child\u27s native language (particularly Spanish) hinders or promotes learning of literacy in English. The authors conduct a four-step process for identifying research on this topic, examining this literature, and then determining the answer to this clinical question. The results suggest that supporting a child\u27s home/native language promotes rather than hinders development of English literacy skills
Patient-specific CFD simulation of intraventricular haemodynamics based on 3D ultrasound imaging
Background: The goal of this paper is to present a computational fluid dynamic (CFD) model with moving boundaries to study the intraventricular flows in a patient-specific framework. Starting from the segmentation of real-time transesophageal echocardiographic images, a CFD model including the complete left ventricle and the moving 3D mitral valve was realized. Their motion, known as a function of time from the segmented ultrasound images, was imposed as a boundary condition in an Arbitrary Lagrangian-Eulerian framework.
Results: The model allowed for a realistic description of the displacement of the structures of interest and for an effective analysis of the intraventricular flows throughout the cardiac cycle. The model provides detailed intraventricular flow features, and highlights the importance of the 3D valve apparatus for the vortex dynamics and apical flow.
Conclusions: The proposed method could describe the haemodynamics of the left ventricle during the cardiac cycle. The methodology might therefore be of particular importance in patient treatment planning to assess the impact of mitral valve treatment on intraventricular flow dynamics
Patient-specific computational fluid dynamic simulation of intraventricular hemodynamics : introducing mitral valve motion as prescribed boundary condition
Compact Toroidal Ion Trap Design and Optimization
We present the design of a new type of compact toroidal, or "halo", ion trap.
Such traps may be useful for mass spectrometry, studying small Coulomb cluster
rings, quantum information applications, or other quantum simulations where a
ring topology is of interest. We present results from a Monte Carlo
optimization of the trap design parameters using finite-element analysis
simulations that minimizes higher-order anharmonic terms in the trapping
pseudopotential, while maintaining complete control over ion placement at the
pseudopotential node in 3D using static bias fields. These simulations are
based on a practical electrode design using readily-available parts, yet can be
easily scaled to any size trap with similar electrode spacings. We also derive
the conditions for a crystal phase transition for two ions in the compact halo
trap, the first non-trivial phase transition for Coulomb crystals in this
geometry.Comment: 8 pages, 9 figure
Strain-Modified RKKY Interaction in Carbon Nanotubes
For low-dimensional metallic structures, such as nanotubes, the exchange
coupling between localized magnetic dopants is predicted to decay slowly with
separation. The long-range character of this interaction plays a significant
role in determining the magnetic order of the system. It has previously been
shown that the interaction range depends on the conformation of the magnetic
dopants in both graphene and nanotubes. Here we examine the RKKY interaction in
carbon nanotubes in the presence of uniaxial strain for a range of different
impurity configurations. We show that strain is capable of amplifying or
attenuating the RKKY interaction, significantly increasing certain interaction
ranges, and acting as a switch: effectively turning on or off the interaction.
We argue that uniaxial strain can be employed to significantly manipulate
magnetic interactions in carbon nanotubes, allowing an interplay between
mechanical and magnetic properties in future spintronic devices. We also
examine the dimensional relationship between graphene and nanotubes with
regards to the decay rate of the RKKY interaction.Comment: 7 pages, 6 figures, submitte
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