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A Theory of Dynamic Selective Vigilance and Preference Reversal, Based on the Example of New Coke
A neural network theory of preference reversal is presented. This theory includes a model of why New Coke was preferred to Old Coke on taste tests but was unpopular in the market. The model uses competing drive lod representing "excitement" and "security." Context influences which drive wins the competition, hence, which stimulus attributes are attended to. Our network's design, outlined m stages, is based on Grossberg's gated dipole theory. Three sets of dipoles, representing attributes, categories, and drives, are connected by modifiable associative synapses. The network also includes competition among categories and enhancement oi attention by mismatch of expectation
Direct observation of domain wall structures in curved permalloy wires containing an antinotch
The formation and field response of head-to-head domain walls in curved permalloy wires, fabricated to contain a single antinotch, have been investigated using Lorentz microscopy. High spatial resolution maps of the vector induction distribution in domain walls close to the antinotch have been derived and compared with micromagnetic simulations. In wires of 10 nm thickness the walls are typically of a modified asymmetric transverse wall type. Their response to applied fields tangential to the wire at the antinotch location was studied. The way the wall structure changes depends on whether the field moves the wall away from or further into the notch. Higher fields are needed and much more distorted wall structures are observed in the latter case, indicating that the antinotch acts as an energy barrier for the domain wal
Process evaluation of a multicomponent dyadic intervention study with exercise and support for people with dementia and their family caregivers
BACKGROUND: A randomized controlled trial of a multicomponent dyadic intervention (a translated and adapted version of an intervention that has been shown to be effective for people with dementia in the USA) was performed. The exercise and support intervention was intended to reduce depressive symptoms of people with dementia and their caregivers. The purpose of this process evaluation is to create in-depth insight into the delivery of the intervention and the effect analysis, to prevent drawing inappropriate conclusions on the efficacy or effectiveness of the intervention, and to formulate recommendations for future studies on complex geriatric interventions. METHODS: Qualitative and quantitative data were collected. The process evaluation was performed according to the model presented by Reelick and colleagues, which encompasses the following three process components: (1) success rate of recruitment and quality of the study population; (2) the quality of execution of the complex intervention; and (3) the process of acquisition of the data. RESULTS: The study design met high research standards and the intervention was carefully delivered. Evaluation of the study population quality revealed a profound recruitment process resulting in a reasonable sample size. Attrition rate during follow-up was acceptable. With regard to the evaluation of the intervention quality, most interviewed participants experienced benefits of the intervention. Attendance at the home visits was high and attrition to homework was moderate. Evaluation of the data acquisition showed the positive value of the use of a mixed design; qualitative analysis of the intervention revealed outcomes not measured in the quantitative analysis. CONCLUSIONS: The process evaluation revealed a carefully and soundly performed study. The mixed design contributed to valuable insights. However, there were some restrictions worth considering. The intervention components may have a different feasibility by moderate attrition to homework and some negative experiences of participants, which may be an indication of too intensive an intervention for this frail population in this specific country. As a result, the results of the statistical effect analysis should be interpreted with caution. TRIAL REGISTRATION: The study has been registered at the Netherlands National Trial Register: NTR1802, registration date 6 May 2009
Multiple Transitions to Chaos in a Damped Parametrically Forced Pendulum
We study bifurcations associated with stability of the lowest stationary
point (SP) of a damped parametrically forced pendulum by varying
(the natural frequency of the pendulum) and (the amplitude of the external
driving force). As is increased, the SP will restabilize after its
instability, destabilize again, and so {\it ad infinitum} for any given
. Its destabilizations (restabilizations) occur via alternating
supercritical (subcritical) period-doubling bifurcations (PDB's) and pitchfork
bifurcations, except the first destabilization at which a supercritical or
subcritical bifurcation takes place depending on the value of . For
each case of the supercritical destabilizations, an infinite sequence of PDB's
follows and leads to chaos. Consequently, an infinite series of period-doubling
transitions to chaos appears with increasing . The critical behaviors at the
transition points are also discussed.Comment: 20 pages + 7 figures (available upon request), RevTex 3.
Magnetic domain-wall motion by propagating spin waves
We found by micromagnetic simulations that the motion of a transverse wall
(TW) type domain wall in magnetic thin-film nanostripes can be manipulated via
interaction with spin waves (SWs) propagating through the TW. The velocity of
the TW motion can be controlled by changes of the frequency and amplitude of
the propagating SWs. Moreover, the TW motion is efficiently driven by specific
SW frequencies that coincide with the resonant frequencies of the local modes
existing inside the TW structure. The use of propagating SWs, whose frequencies
are tuned to those of the intrinsic TW modes, is an alternative approach for
controlling TW motion in nanostripes
Direct current control of three magnon scattering processes in spin-valve nanocontacts
We have investigated the generation of spin waves in the free layer of an
extended spin-valve structure with a nano-scaled point contact driven by both
microwave and direct electric current using Brillouin light scattering
microscopy. Simultaneously with the directly excited spin waves, strong
nonlinear effects are observed, namely the generation of eigenmodes with
integer multiple frequencies (2 \emph{f}, 3 \emph{f}, 4 \emph{f}) and modes
with non-integer factors (0.5 \emph{f}, 1.5 \emph{f}) with respect to the
excitation frequency \emph{f}. The origin of these nonlinear modes is traced
back to three magnon scattering processes. The direct current influence on the
generation of the fundamental mode at frequency \emph{f} can be related to the
spin-transfer torque, while the efficiency of three-magnon-scattering processes
is controlled by the Oersted field as an additional effect of the direct
current
Interpreting gaps: a geoarchaeological point of view on the Gravettian record of Ach and Lone valleys (Swabian Jura, SW Germany)
Unlike other Upper Paleolithic industries, Gravettian assemblages from the Swabian Jura are documented solely
in the Ach Valley (35-30 Kcal BP). On the other hand, traces of contemporaneous occupations in the nearby Lone
Valley are sparse. It is debated whether this gap is due to a phase of human depopulation, or taphonomic issues
related with landscape changes.
In this paper we present ERT, EC-logging and GPR data showing that in both Ach and Lone valleys sediments
and archaeological materials eroded from caves and deposited above river incisions after 37-32 Kcal BP. We
argued that the rate of cave erosion was higher after phases of downcutting, when hillside erosion was more
intensive. To investigate on the causes responsible for the dearth of Gravettian materials in the Lone Valley we
test two alternative hypotheses: i) Gravettian humans occupied less intensively this part of the Swabian Jura. ii)
Erosion of cave deposits did not occur at the same time in the two valleys. We conclude that the second hypothesis
is most likely. Ages from the Lone Valley show increasing multimillennial gaps between 36 and 18 Kcal
BP, while a similar gap is present in the Ach Valley between 28 and 16 Kcal BP. Based on geoarchaeological data
from previous studies and presented in this paper, we interpreted these gaps in radiocarbon data as indicating of
cave erosion. Furthermore, we argued that the time difference across the two valleys show that the erosion of
cave deposits began and terminated earlier in the Lone Valley, resulting in a more intensive removal of
Gravettian-aged deposits. The hypothesis that cave erosion was triggered by regional landscape changes seems to
be supported by geochronological data from the Danube Valley, which show that terrace formation at the end of
the Pleistocene moved westwards throughout southern Germany with a time lag of few millennia.PTDC/HAR-ARQ/27833/2017info:eu-repo/semantics/publishedVersio
A spin-wave frequency doubler by domain wall oscillation
We present a new mechanism for spin-wave excitation using a pinned domain
wall which is forced to oscillate at its eigenfrequency and radiates spin
waves. The domain wall acts as a frequency doubler, as the excited spin waves
have twice the frequency of the domain wall oscillation. The investigations
have been carried out using micromagnetic simulations and enable the
determination of the main characteristics of the excited spin-waves such as
frequency, wavelength, and velocity. This behavior is understood by the
oscillation in the perpendicular magnetization which shows two anti-nodes
oscillating out of phase with respect to each other.Comment: 8 pages, 3 figure
Parameterized Complexity of Maximum Edge Colorable Subgraph
A graph is {\em -edge colorable} if there is a coloring , such that for distinct , we have
. The {\sc Maximum Edge-Colorable Subgraph} problem
takes as input a graph and integers and , and the objective is to
find a subgraph of and a -edge-coloring of , such that . We study the above problem from the viewpoint of Parameterized
Complexity. We obtain \FPT\ algorithms when parameterized by: the vertex
cover number of , by using {\sc Integer Linear Programming}, and ,
a randomized algorithm via a reduction to \textsc{Rainbow Matching}, and a
deterministic algorithm by using color coding, and divide and color. With
respect to the parameters , where is one of the following: the
solution size, , the vertex cover number of , and l -
{\mm}(G), where {\mm}(G) is the size of a maximum matching in ; we show
that the (decision version of the) problem admits a kernel with vertices. Furthermore, we show that there is no kernel of size
, for any and computable
function , unless \NP \subseteq \CONPpoly
The First Space-Based Gravitational-Wave Detectors
Gravitational waves provide a laboratory for general relativity and a window
to energetic astrophysical phenomena invisible with electromagnetic radiation.
Several terrestrial detectors are currently under construction, and a
space-based interferometer is envisioned for launch early next century to
detect test-mass motions induced by waves of relatively short wavelength.
Very-long-wavelength gravitational waves can be detected using the plasma in
the early Universe as test masses; the motion induced in the plasma by a wave
is imprinted onto the cosmic microwave background (CMB). While the signature of
gravitational waves on the CMB temperature fluctuations is not unique, the
polarization pattern can be used to unambiguously detect gravitational
radiation. Thus, forthcoming CMB polarization experiments, such as MAP and
Planck, will be the first space-based gravitational-wave detectors.Comment: 5 pages, 3 postscript figure
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