113,526 research outputs found
Can we use starlings' aversion to eyespots as the basis for a novel 'cognitive bias' task?
Experiments in humans have shown that changes in emotional (affective) state cause adaptive changes in the processing of incoming information, termed "cognitive bias". For instance, the states of anxiety and depression have been shown to be associated with "pessimistic" judgements of ambiguous stimuli intermediate between stimuli associated with positive and negative outcomes. This phenomenon provides a promising method for objectively assessing animal emotional states and has been successfully demonstrated in preliminary studies. However, the experiments yielding these results required extensive training to establish the necessary positive and negative associations. Here we present an experiment using responses to eyespot stimuli that are naturally aversive to many bird species, and require no explicit associative training. We manipulated the state of wild-caught European starlings (Sturnus vulgaris) by playing one of four possible sounds: starling "threat call" (control manipulation), a sparrowhawk call (i.e. predator), starling alarm call or white noise, on the assumption that the latter three sounds would cause anxiety. Immediately following the auditory stimulus, we recorded the birds' behaviour in the presence of each of three visual stimuli: eyespots, ambiguous eyespots or no eyespots. We hypothesised that there would be an interaction between the state of the birds and their response to eyespots, with birds showing enhanced aversion to ambiguous eyespots when anxious. We found evidence that white noise and alarm calls generated anxiety, and that eyespots were aversive. However, there was no interaction between state and response to eyespots. In an attempt to understand our failure to obtain the predicted cognitive bias, we discuss evidence that the aversive nature of eyespots is not attributable to predator mimicry, and is therefore not modulated by anxiety. © 2009 Elsevier B.V. All rights reserved
Min-Max Theorems for Packing and Covering Odd -trails
We investigate the problem of packing and covering odd -trails in a
graph. A -trail is a -walk that is allowed to have repeated
vertices but no repeated edges. We call a trail odd if the number of edges in
the trail is odd. Let denote the maximum number of edge-disjoint odd
-trails, and denote the minimum size of an edge-set that
intersects every odd -trail.
We prove that . Our result is tight---there are
examples showing that ---and substantially improves upon
the bound of obtained in [Churchley et al 2016] for .
Our proof also yields a polynomial-time algorithm for finding a cover and a
collection of trails satisfying the above bounds.
Our proof is simple and has two main ingredients. We show that (loosely
speaking) the problem can be reduced to the problem of packing and covering odd
-trails losing a factor of 2 (either in the number of trails found, or
the size of the cover). Complementing this, we show that the
odd--trail packing and covering problems can be tackled by exploiting
a powerful min-max result of [Chudnovsky et al 2006] for packing
vertex-disjoint nonzero -paths in group-labeled graphs
Massive spin 2 propagator on de Sitter space
We compute the Pauli-Jordan, Hadamard and Feynman propagators for the massive
metrical perturbations on de Sitter space. They are expressed both in terms of
mode sums and in invariant forms.Comment: 30 pages + 1 eps fi
Gray-matter volume, midbrain dopamine D2/D3 receptors and drug craving in methamphetamine users.
Dysfunction of the mesocorticolimbic system has a critical role in clinical features of addiction. Despite evidence suggesting that midbrain dopamine receptors influence amphetamine-induced dopamine release and that dopamine is involved in methamphetamine-induced neurotoxicity, associations between dopamine receptors and gray-matter volume have been unexplored in methamphetamine users. Here we used magnetic resonance imaging and [(18)F]fallypride positron emission tomography, respectively, to measure gray-matter volume (in 58 methamphetamine users) and dopamine D2/D3 receptor availability (binding potential relative to nondisplaceable uptake of the radiotracer, BPnd) (in 31 methamphetamine users and 37 control participants). Relationships between these measures and self-reported drug craving were examined. Although no difference in midbrain D2/D3 BPnd was detected between methamphetamine and control groups, midbrain D2/D3 BPnd was positively correlated with gray-matter volume in the striatum, prefrontal cortex, insula, hippocampus and temporal cortex in methamphetamine users, but not in control participants (group-by-midbrain D2/D3 BPnd interaction, P<0.05 corrected for multiple comparisons). Craving for methamphetamine was negatively associated with gray-matter volume in the insula, prefrontal cortex, amygdala, temporal cortex, occipital cortex, cerebellum and thalamus (P<0.05 corrected for multiple comparisons). A relationship between midbrain D2/D3 BPnd and methamphetamine craving was not detected. Lower midbrain D2/D3 BPnd may increase vulnerability to deficits in gray-matter volume in mesocorticolimbic circuitry in methamphetamine users, possibly reflecting greater dopamine-induced toxicity. Identifying factors that influence prefrontal and limbic volume, such as midbrain BPnd, may be important for understanding the basis of drug craving, a key factor in the maintenance of substance-use disorders
Influence of measurement volume on predicted attrition by the distinct element method
During agitated drying and mixing processes, particle beds are exposed to shear deformation. This leads to particle attrition, the extent of which is dependent on the prevailing stresses and strains in the bed. The distributions of shear stresses and strain rates within the bed are highly non-uniform, requiring attention to localised conditions. Therefore a narrow angular sector of the bed is divided radially and vertically into a number of measurement cells, within which the stresses and strain rates are calculated throughout one rotation by the Distinct Element Method. These are then used in an empirical relationship of material breakage to predict the extent of attrition due to agitation. Here we investigate the influence of the measurement cell size on the estimated stresses and strain rates, and the subsequent effect on the predicted attrition. The measurement cell size is altered by varying the measurement sector size and the number of radial and vertical divisions within it. The median particle size is also varied to establish its influence on the predicted attrition. An increase in the average number of particles in a given cell, by varying the particle size or measurement cell dimensions, leads to a reduction in the estimated stresses and strain rates, and therefore a reduction in the predicted attrition. Comparison of the predicted attrition with the experimental breakage in the agitated vessel shows that the prediction method is accurate when the cell dimensions are comparable to the width of a naturally occurring shear band
Collaborative working in highways major maintenance projects
Over the last decade, there has been a growing emphasis on collaborations and partnering in the construction industry. This has been embraced in the UK highways maintenance sector, with partnering promoted by the client, leading to the formation of alliances and partnering frameworks. One of these is the construction management framework (CMF), the preferred method of procurement for major maintenance projects in the Highways Agency’s areas 9 and 10. This paper compares two road and structure renewals schemes carried out using the CMF. The first scheme was carried out in 2004 as one of the first of its type to be undertaken by the CMF; the second was a similar project carried out in 2006. Documentation of the two projects was reviewed to identify the benefits that were gained through working in collaboration, and if there was an improvement in performance as the framework became more established. The research considered key performance indicators, including cost and time predictability measures, respect for people surveys, innovations and lessons learned discussed at the time of the projects, and instructions for changes to works information. Data collected from both schemes show improvements in measurement and culture fostered by the CMF, and the advantages of the processes used are illustrated
Classical diffusion of N interacting particles in one dimension: General results and asymptotic laws
I consider the coupled one-dimensional diffusion of a cluster of N classical
particles with contact repulsion. General expressions are given for the
probability distributions, allowing to obtain the transport coefficients. In
the limit of large N, and within a gaussian approximation, the diffusion
constant is found to behave as N^{-1} for the central particle and as (\ln
N)^{-1} for the edge ones. Absolute correlations between the edge particles
increase as (\ln N)^{2}. The asymptotic one-body distribution is obtained and
discussed in relation of the statistics of extreme events.Comment: 6 pages, 2 eps figure
Non-invasive acquisition of fetal ECG from the maternal xyphoid process: a feasibility study in pregnant sheep and a call for open data sets
Objective: The utility of fetal heart rate (FHR) monitoring can only be
achieved with an acquisition sampling rate that preserves the underlying
physiological information on the millisecond time scale (1000 Hz rather than 4
Hz). For such acquisition, fetal ECG (fECG) is required, rather than the
ultrasound to derive FHR. We tested one recently developed algorithm, SAVER,
and two widely applied algorithms to extract fECG from a single channel
maternal ECG signal recorded over the xyphoid process rather than the routine
abdominal signal. Approach: At 126dG, ECG was attached to near-term ewe and
fetal shoulders, manubrium and xyphoid processes (n=12). FECG served as the
ground-truth to which the fetal ECG signal extracted from the
simultaneously-acquired maternal ECG was compared. All fetuses were in good
health during surgery (pH 7.29+/-0.03, pO2 33.2+/-8.4, pCO2 56.0+/-7.8, O2Sat
78.3+/-7.6, lactate 2.8+/-0.6, BE -0.3+/-2.4). Main result: In all animals,
single lead fECG extraction algorithm could not extract fECG from the maternal
ECG signal over the xyphoid process with the F1 less than 50%. Significance:
The applied fECG extraction algorithms might be unsuitable for the maternal ECG
signal over the xyphoid process, or the latter does not contain strong enough
fECG signal, although the lead is near the mother's abdomen. Fetal sheep model
is widely used to mimic various fetal conditions, yet ECG recordings in a
public data set form are not available to test the predictive ability of fECG
and FHR. We are making this data set openly available to other researchers to
foster non-invasive fECG acquisition in this animal model
Narrowing the wingless-2 mutation to a 227 kb candidate region on chicken chromosome 12.
Wingless-2 (wg-2) is an autosomal recessive mutation in chicken that results in an embryonic lethal condition. Affected individuals exhibit a multisystem syndrome characterized by absent wings, truncated legs, and craniofacial, kidney, and feather malformations. Previously, work focused on phenotype description, establishing the autosomal recessive pattern of Mendelian inheritance and placing the mutation on an inbred genetic background to create the congenic line UCD Wingless-2.331. The research described in this paper employed the complementary tools of breeding, genetics, and genomics to map the chromosomal location of the mutation and successively narrow the size of the region for analysis of the causative element. Specifically, the wg-2 mutation was initially mapped to a 7 Mb region of chromosome 12 using an Illumina 3 K SNP array. Subsequent SNP genotyping and exon sequencing combined with analysis from improved genome assemblies narrowed the region of interest to a maximum size of 227 kb. Within this region, 3 validated and 3 predicted candidate genes are found, and these are described. The wg-2 mutation is a valuable resource to contribute to an improved understanding of the developmental pathways involved in chicken and avian limb development as well as serving as a model for human development, as the resulting syndrome shares features with human congenital disorders
Conditional Image-Text Embedding Networks
This paper presents an approach for grounding phrases in images which jointly
learns multiple text-conditioned embeddings in a single end-to-end model. In
order to differentiate text phrases into semantically distinct subspaces, we
propose a concept weight branch that automatically assigns phrases to
embeddings, whereas prior works predefine such assignments. Our proposed
solution simplifies the representation requirements for individual embeddings
and allows the underrepresented concepts to take advantage of the shared
representations before feeding them into concept-specific layers. Comprehensive
experiments verify the effectiveness of our approach across three phrase
grounding datasets, Flickr30K Entities, ReferIt Game, and Visual Genome, where
we obtain a (resp.) 4%, 3%, and 4% improvement in grounding performance over a
strong region-phrase embedding baseline.Comment: ECCV 2018 accepted pape
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