32,661 research outputs found
Variability in wrist-tilt accelerometer based gesture interfaces
In this paper we describe a study that examines human performance in a tilt control targeting task on a PDA. A three-degree of freedom accelerometer attached to the base of the PDA allows users to navigate to the targets by tilting their wrist in different directions. Post hoc analysis of performance data has been used to classify the ease of targeting and variability of movement in the different directions. The results show that there is an increase in variability of motions upwards from the centre, compared to downwards motions. Also the variability in the x axis component of the motion was greater than that in the y axis. This information can be used to guide designers as to the ease of various relative motions, and can be used to reshape the dynamics of the interaction to make each direction equally easy to achieve
Applicability of fluidic controls to a Rankine cycle automotive engine Final report
Fluidic controls for automotive engine examined by Rankine cycle performance with water, CP-34, and freon TF and investigation for boiler and feed pump control criteri
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Cortisol levels in response to starting school in children at increased risk for social phobia
Background: Research on depression has identified hyperactivity of the HPA axis as a
potential contributory factor to the intergenerational transmission of affective symptoms. However,
this has not yet been examined in the context of social phobia. The current study compared HPA axis
activity in response to a universal social stressor (starting school) in children of 2 groups of women:
one with social phobia and one with no history of anxiety (comparison group). To determine specificity
of effects of maternal social phobia, a third group of children were also examined whose mothers had
generalised anxiety disorder (GAD).
Method: Children provided salivary cortisol samples in the morning, afternoon and at bedtime across 3
time-blocks surrounding the school start: a month before starting school (baseline), the first week at
school (stress response), and the end of the first school term (stress recovery). Child behavioural
inhibition at 14 months was also assessed to explore the influence of early temperament on later stress
responses.
Results: All children displayed an elevation in morning and afternoon cortisol from baseline during the
first week at school, which remained elevated until the end of the first term. Children in the social
phobia group, however, also displayed an equivalent elevation in bedtime cortisol, which was not
observed for comparison children or for children of mothers with GAD. Children in the social phobia
group who were classified as 'inhibited' at 14 months displayed significantly higher afternoon cortisol
levels overall.
Summary: A persistent stress response to school in the morning and afternoon is typical for all
children, but children of mothers with social phobia also display atypical elevations in evening cortisol
levels when at school - signalling long-term disruption of the circadian rhythm in HPA axis activity.
This is the first study to report HPA axis disruption in children at risk of developing social phobia, and
future research should aim to determine whether this represents a pathway for symptom
development, taking early temperament into account
Dynamic phase transition in the conversion of B-DNA to Z-DNA
The long time dynamics of the conformational transition from B-DNA to Z-DNA
is shown to undergo a dynamic phase transition. We obtained the dynamic phase
diagram for the stability of the front separating B and Z. The instability in
this front results in two split fronts moving with different velocities. Hence,
depending on the system parameters a denatured state may develop dynamically
eventhough it is thermodynamically forbidden. This resolves the current
controversies on the transition mechanism of the B-DNA to Z-DNA.Comment: 5 pages, 4 figures. New version with correction of typos, new
references, minor modifications in Fig 2, 3. To appear in EP
Field Theory of Propagating Reaction-Diffusion Fronts
The problem of velocity selection of reaction-diffusion fronts has been
widely investigated. While the mean field limit results are well known
theoretically, there is a lack of analytic progress in those cases in which
fluctuations are to be taken into account. Here, we construct an analytic
theory connecting the first principles of the reaction-diffusion process to an
effective equation of motion via field-theoretic arguments, and we arrive at
the results already confirmed by numerical simulations
Limit cycles in the presence of convection, a travelling wave analysis
We consider a diffusion model with limit cycle reaction functions, in the
presence of convection. We select a set of functions derived from a realistic
reaction model: the Schnakenberg equations. This resultant form is
unsymmetrical. We find a transformation which maps the irregular equations into
model form. Next we transform the dependent variables into polar form. From
here, a travelling wave analysis is performed on the radial variable. Results
are complex, but we make some simple estimates.
We carry out numerical experiments to test our analysis. An initial `knock'
starts the propagation of pattern. The speed of the travelling wave is not
quite as expected. We investigate further. The system demonstrates distinctly
different behaviour to the left and the right. We explain how this phenomenon
occurs by examining the underlying behaviour.Comment: 20 pages, 5 figure
Horseshoe-based Bayesian nonparametric estimation of effective population size trajectories
Phylodynamics is an area of population genetics that uses genetic sequence
data to estimate past population dynamics. Modern state-of-the-art Bayesian
nonparametric methods for recovering population size trajectories of unknown
form use either change-point models or Gaussian process priors. Change-point
models suffer from computational issues when the number of change-points is
unknown and needs to be estimated. Gaussian process-based methods lack local
adaptivity and cannot accurately recover trajectories that exhibit features
such as abrupt changes in trend or varying levels of smoothness. We propose a
novel, locally-adaptive approach to Bayesian nonparametric phylodynamic
inference that has the flexibility to accommodate a large class of functional
behaviors. Local adaptivity results from modeling the log-transformed effective
population size a priori as a horseshoe Markov random field, a recently
proposed statistical model that blends together the best properties of the
change-point and Gaussian process modeling paradigms. We use simulated data to
assess model performance, and find that our proposed method results in reduced
bias and increased precision when compared to contemporary methods. We also use
our models to reconstruct past changes in genetic diversity of human hepatitis
C virus in Egypt and to estimate population size changes of ancient and modern
steppe bison. These analyses show that our new method captures features of the
population size trajectories that were missed by the state-of-the-art methods.Comment: 36 pages, including supplementary informatio
Hopping Conduction and Bacteria: Transport in Disordered Reaction-Diffusion Systems
We report some basic results regarding transport in disordered
reaction-diffusion systems with birth (A->2A), death (A->0), and binary
competition (2A->A) processes. We consider a model in which the growth process
is only allowed to take place in certain areas--"oases"--while the rest of
space--the "desert"--is hostile to growth. In the limit of low oasis density,
transport is mediated through rare "hopping" events, necessitating the
inclusion of discreteness effects in the model. By first considering transport
between two oases, we are able to derive an approximate expression for the
average time taken for a population to traverse a disordered medium.Comment: 4 pages, 2 figure
Kaon Photoproduction and the Decay Parameter
The weak decay parameter of the is an important quantity
for the extraction of polarization observables in various experiments.
Moreover, in combination with from decay it provides a
measure for matter-antimatter asymmetry. The weak decay parameter also affects
the decay parameters of the and baryons and, in general, any
quantity in which the polarization of the is relevant. The recently
reported value by the BESIII collaboration of is significantly
larger than the previous PDG value of that had been accepted and
used for over 40 years. In this work we make an independent estimate of
, using an extensive set of polarization data measured in kaon
photoproduction in the baryon resonance region and constraints set by spin
algebra. The obtained value is 0.721(6)(5). The result is corroborated by
multiple statistical tests as well as a modern phenomenological model, showing
that our new value yields the best description of the data in question. Our
analysis supports the new BESIII finding that is significantly
larger than the previous PDG value. Any experimental quantity relying on the
value of should therefore be re-considered.Comment: 6 pages, 1 figure
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