854 research outputs found
An evaluation of respondent conditioning procedures to decrease barking in an animal shelter
A common problem behavior in animal shelters is excessive noise from barking, which can regularly exceed 100dBs. Noise levels in animal shelters are correlated with increased stress in dogs, which may lead to increased problem behavior and a decrease in adoption. The purpose of the current study was to evaluate the use of respondent conditioning procedures to reduce barking noise level in an animal shelter by pairing a door chime with edible items. Following a baseline and neutral stimulus phase, the door chime was paired with edible items over a period of three weeks. Following this pairing phase, the pairing was stopped to determine if the door chime would act as a conditioned stimulus and reduce barking. These procedures were replicated following an additional baseline phase. Overall, the procedure was effective in reducing the noise level of the kennel area as compared to baseline levels. Implications and future research areas are discussed
Application of the ADAPTED FRISCO framework in case-based learning activities
Acquisition of clinical skills is of upmost importance for health sciences profes- sionals, and a guarantee that safe and effective patient care will be provided. Clinical competencies may encompass a series of skills that are introduced through graduation and developed during professional activity, namely the technical skills, communication skills, clinical reasoning and reflexion in daily practice. Therefore, clinical competence is not a static skill, but it grows with practice and is lifelong learning. Case-based learning is frequently used to en- hance learning in clinical reasoning and judgment for rational decision-making, competencies that are also associated to critical thinking. To be effective, case- based activities need to be structured, the learning objectives adjusted to each situation and students sought to be guided throughout the activity, so that they are actively engaged in the learning process bridging learning to professional environments. In this paper the authors present a model for a case-based activity aiming to enhance clinical competency in health science students. Framed by the application of the FRISCO guidelines adapted in previous work, the au- thors illustrate, by an example, how, in the proposed activity, congruence may be achieved among intended learning, instructional activities, and assessment methods while teaching diagnostic reasoning to health sciences students. Keywords: critical thinking; case-studies learning; health science
Gauge Invariant Factorisation and Canonical Quantisation of Topologically Massive Gauge Theories in Any Dimension
Abelian topologically massive gauge theories (TMGT) provide a topological
mechanism to generate mass for a bosonic p-tensor field in any spacetime
dimension. These theories include the 2+1 dimensional Maxwell-Chern-Simons and
3+1 dimensional Cremmer-Scherk actions as particular cases. Within the
Hamiltonian formulation, the embedded topological field theory (TFT) sector
related to the topological mass term is not manifest in the original phase
space. However through an appropriate canonical transformation, a gauge
invariant factorisation of phase space into two orthogonal sectors is feasible.
The first of these sectors includes canonically conjugate gauge invariant
variables with free massive excitations. The second sector, which decouples
from the total Hamiltonian, is equivalent to the phase space description of the
associated non dynamical pure TFT. Within canonical quantisation, a likewise
factorisation of quantum states thus arises for the full spectrum of TMGT in
any dimension. This new factorisation scheme also enables a definition of the
usual projection from TMGT onto topological quantum field theories in a most
natural and transparent way. None of these results rely on any gauge fixing
procedure whatsoever.Comment: 1+25 pages, no figure
Dynamics and transport in random quantum systems governed by strong-randomness fixed points
We present results on the low-frequency dynamical and transport properties of
random quantum systems whose low temperature (), low-energy behavior is
controlled by strong disorder fixed points. We obtain the momentum and
frequency dependent dynamic structure factor in the Random Singlet (RS) phases
of both spin-1/2 and spin-1 random antiferromagnetic chains, as well as in the
Random Dimer (RD) and Ising Antiferromagnetic (IAF) phases of spin-1/2 random
antiferromagnetic chains. We show that the RS phases are unusual `spin metals'
with divergent low-frequency spin conductivity at T=0, and we also follow the
conductivity through novel `metal-insulator' transitions tuned by the strength
of dimerization or Ising anisotropy in the spin-1/2 case, and by the strength
of disorder in the spin-1 case. We work out the average spin and energy
autocorrelations in the one-dimensional random transverse field Ising model in
the vicinity of its quantum critical point. All of the above calculations are
valid in the frequency dominated regime \omega \agt T, and rely on previously
available renormalization group schemes that describe these systems in terms of
the properties of certain strong-disorder fixed point theories. In addition, we
obtain some information about the behavior of the dynamic structure factor and
dynamical conductivity in the opposite `hydrodynamic' regime for
the special case of spin-1/2 chains close to the planar limit (the quantum x-y
model) by analyzing the corresponding quantities in an equivalent model of
spinless fermions with weak repulsive interactions and particle-hole symmetric
disorder.Comment: Long version (with many additional results) of Phys. Rev. Lett. {\bf
84}, 3434 (2000) (available as cond-mat/9904290); two-column format, 33 pages
and 8 figure
Magnetic structure and ferroelectric polarization of MnWO4 investigated by density functional calculations and classical spin analysis
The ordered magnetic states of MnWO4 at low temperatures were examined by
evaluating the spin exchange interactions between the Mn2+ ions of MnWO4 on the
basis of first principles density functional calculations and by performing
classical spin analysis with the resulting spin exchange parameters. Our work
shows that the spin exchange interactions are frustrated within each zigzag
chain of Mn2+ ions along the c-direction and between such chains of Mn2+ ions
along the a-direction. This explains the occurrence of a spiral-spin order
along the c- and a-directions in the incommensurate magnetic state AF2, and
that of a uudd spin order along the c- and a-directions in the commensurate
magnetic state AF1. The ferroelectric polarization of MnWO4 in the spiral-spin
state AF2 was examined by performing Berry phase calculations for a model
superstructure to find that the ferroelectric polarization occurs along the
b-direction, in agreement with experiment.Comment: 30 pages, 10 figures, 4 figure
Are bone erosions detected by magnetic resonance imaging and ultrasonography true erosions? A comparison with computed tomography in rheumatoid arthritis metacarpophalangeal joints
The objective of the study was, with multidetector computed tomography (CT) as the reference method, to determine whether bone erosions in rheumatoid arthritis (RA) metacarpophalangeal (MCP) joints detected with magnetic resonance imaging (MRI) and ultrasonography (US), but not with radiography, represent true erosive changes. We included 17 RA patients with at least one, previously detected, radiographically invisible MCP joint MRI erosion, and four healthy control individuals. They all underwent CT, MRI, US and radiography of the 2nd to 5th MCP joints of one hand on the same day. Each imaging modality was evaluated for the presence of bone erosions in each MCP joint quadrant. In total, 336 quadrants were examined. The sensitivity, specificity and accuracy, respectively, for detecting bone erosions (with CT as the reference method) were 19%, 100% and 81% for radiography; 68%, 96% and 89% for MRI; and 42%, 91% and 80% for US. When the 16 quadrants with radiographic erosions were excluded from the analysis, similar values for MRI (65%, 96% and 90%) and US (30%, 92% and 80%) were obtained. CT and MRI detected at least one erosion in all patients but none in control individuals. US detected at least one erosion in 15 patients, however, erosion-like changes were seen on US in all control individuals. Nine patients had no erosions on radiography. In conclusion, with CT as the reference method, MRI and US exhibited high specificities (96% and 91%, respectively) in detecting bone erosions in RA MCP joints, even in the radiographically non-erosive joints (96% and 92%). The moderate sensitivities indicate that even more erosions than are seen on MRI and, particularly, US are present. Radiography exhibited high specificity (100%) but low sensitivity (19%). The present study strongly indicates that bone erosions, detected with MRI and US in RA patients, represent a loss of calcified tissue with cortical destruction, and therefore can be considered true bone erosions
Magnetization profiles and NMR spectra of doped Haldane chains at finite temperatures
Open segments of S=1 antiferromagnetic spin chains are studied at finite
temperatures and fields using continuous time Quantum Monte Carlo techniques.
By calculating the resulting magnetization profiles for a large range of chain
lengths with fixed field and temperature we reconstruct the experimentally
measured NMR spectrum of impurity doped YBaNiMgO. For
temperatures above the gap the calculated NMR spectra are in excellent
agreement with the experimental results, confirming the existence of
excitations at the end of open S=1 chain segments. At temperatures below the
gap, neglecting inter chain couplings, we still find well defined peaks in the
calculated NMR spectra corresponding to the chain end excitations. At
low temperatures, inter chain couplings could be important, resulting in a more
complicated phase.Comment: 7 pages, 5 figures, minor correction
Real-time Classification of Vehicle Types within Infra-red Imagery
Real-time classification of vehicles into sub-category types poses a significant challenge within infra-red imagery due to the high levels of intra-class variation in thermal vehicle signatures caused by aspects of design, current operating duration and ambient thermal conditions. Despite these challenges, infra-red sensing offers significant generalized target object detection advantages in terms of all-weather operation and invariance to visual camouflage techniques. This work investigates the accuracy of a number of real-time object classification approaches for this task within the wider context of an existing initial object detection and tracking framework. Specifically we evaluate the use of traditional feature-driven bag of visual words and histogram of oriented gradient classification approaches against modern convolutional neural network architectures. Furthermore, we use classical photogrammetry, within the context of current target detection and classification techniques, as a means of approximating 3D target position within the scene based on this vehicle type classification. Based on photogrammetric estimation of target position, we then illustrate the use of regular Kalman filter based tracking operating on actual 3D vehicle trajectories. Results are presented using a conventional thermal-band infra-red (IR) sensor arrangement where targets are tracked over a range of evaluation scenarios
Comparison of S=0 and S=1/2 Impurities in Haldane Chain Compound,
We present the effect of Zn (S=0) and Cu (S=1/2) substitution at the Ni site
of S=1 Haldane chain compound . Y NMR allows us to
measure the local magnetic susceptibility at different distances from the
defects. The Y NMR spectrum consists of one central peak and several
less intense satellite peaks. The shift of the central peak measures the
uniform susceptibility, which displays a Haldane gap 100 K and it
corresponds to an AF coupling J260 K between the near-neighbor Ni spins.
Zn or Cu substitution does not affect the Haldane gap. The satellites, which
are evenly distributed on the two sides of the central peak, probe the
antiferromagnetic staggered magnetization near the substituted site, which
decays exponentially. Its extension is found identical for both impurities and
corresponds accurately to the correlation length (T) determined by Monte
Carlo (QMC) simulations for the pure compound. In the case of non-magnetic Zn,
the temperature dependence of the induced magnetization is consistent with a
Curie law with an "effective" spin S=0.4 on each side of Zn, which is well
accounted by Quantum Monte Carlo computations of the spinless-defect-induced
magnetism. In the case of magnetic Cu, the similarity of the induced magnetism
to the Zn case implies a weak coupling of the Cu spin to the nearest- neighbor
Ni spins. The slight reductionin the induced polarization with respect to Zn is
reproduced by QMC computations by considering an antiferromagnetic coupling of
strength J'=0.1-0.2 J between the S=1/2 Cu-spin and nearest-neighbor Ni-spin.Comment: 15 pages, 18 figures, submitted to Physical Review
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