8,322 research outputs found
Controlling the uncontrolled: Are there incidental experimenter effects on physiologic responding?
The degree to which experimenters shape participant behavior has long been of interest in experimental social science research. Here, we extend this question to the domain of peripheral psychophysiology, where experimenters often have direct, physical contact with participants, yet researchers do not consistently test for their influence. We describe analytic tools for examining experimenter effects in peripheral physiology. Using these tools, we investigate nine data sets totaling 1,341 participants and 160 experimenters across different roles (e.g., lead research assistants, evaluators, confederates) to demonstrate how researchers can test for experimenter effects in participant autonomic nervous system activity during baseline recordings and reactivity to study tasks. Our results showed (a) little to no significant variance in participants' physiological reactivity due to their experimenters, and (b) little to no evidence that three characteristics of experimenters that are well known to shape interpersonal interactions-status (using five studies with 682 total participants), gender (using two studies with 359 total participants), and race (in two studies with 554 total participants)-influenced participants' physiology. We highlight several reasons that experimenter effects in physiological data are still cause for concern, including the fact that experimenters in these studies were already restricted on a number of characteristics (e.g., age, education). We present recommendations for examining and reducing experimenter effects in physiological data and discuss implications for replication
DEVELOPMENT OF COMPOSITE MATERIAL FROM TIRE SCRAPES AND LATEX FOR APPLICATION IN THERMAL INSULATION
Given the unquestionable need of environmental preservation of discarded industrial residues, the scrape of tires, have been seen as a salutary alternative for addictive in concrete, asphalt production and of other composites materials. In this work, grew a composite the base of scrape of tire as reinforcement and latex as matrix, to be used as insulating thermal in"cold" systems (0º C). Analyzed the acting of the material was what plays the thermal conservation when submitted the flow of heat. Verified the temperature profiles in the internal surfaces and it expresses of the composite as well as the temperature gradient in the same. As consequence, in function of the answers of the system, conclusions were reached
Constraints on the IR behavior of the gluon propagator in Yang-Mills theories
We present rigorous upper and lower bounds for the zero-momentum gluon
propagator D(0) of Yang-Mills theories in terms of the average value of the
gluon field. This allows us to perform a controlled extrapolation of lattice
data to infinite volume, showing that the infrared limit of the Landau-gauge
gluon propagator in SU(2) gauge theory is finite and nonzero in three and in
four space-time dimensions. In the two-dimensional case we find D(0) = 0, in
agreement with Ref. [1]. We suggest an explanation for these results. We note
that our discussion is general, although we only apply our analysis to pure
gauge theory in Landau gauge. Simulations have been performed on the IBM
supercomputer at the University of Sao Paulo.Comment: 4 pages, 3 figures, 1 tabl
Flexible construction of hierarchical scale-free networks with general exponent
Extensive studies have been done to understand the principles behind
architectures of real networks. Recently, evidences for hierarchical
organization in many real networks have also been reported. Here, we present a
new hierarchical model which reproduces the main experimental properties
observed in real networks: scale-free of degree distribution (frequency
of the nodes that are connected to other nodes decays as a power-law
) and power-law scaling of the clustering coefficient
. The major novelties of our model can be summarized as
follows: {\it (a)} The model generates networks with scale-free distribution
for the degree of nodes with general exponent , and arbitrarily
close to any specified value, being able to reproduce most of the observed
hierarchical scale-free topologies. In contrast, previous models can not obtain
values of . {\it (b)} Our model has structural flexibility
because {\it (i)} it can incorporate various types of basic building blocks
(e.g., triangles, tetrahedrons and, in general, fully connected clusters of
nodes) and {\it (ii)} it allows a large variety of configurations (i.e., the
model can use more than copies of basic blocks of nodes). The
structural features of our proposed model might lead to a better understanding
of architectures of biological and non-biological networks.Comment: RevTeX, 5 pages, 4 figure
The Hydra I cluster core - II. Kinematic complexity in a rising velocity dispersion profile around the cD galaxy NGC 3311
NGC 3311, the central galaxy of the Hydra I cluster, shows signatures of
recent infall of satellite galaxies from the cluster environment. Previous work
has shown that the line-of-sight velocity dispersion of the stars and globular
clusters in the extended halo of NGC 3311 rises up to the value of the cluster
velocity dispersion. We performed multi-object spectroscopic observations of
the diffuse stellar halo of NGC 3311 using VLT/FORS2 in MXU mode to mimic a
coarse `IFU'. We use pPXF to extract the kinematic information. We find a
homogeneous velocity and velocity dispersion field within r<10 kpc. Beyond this
radius, both the velocities and dispersions start to depend on azimuth angle
and show a significant intrinsic scatter. The inner spheroid of NGC 3311 can be
described as a slow rotator. Outside 10 kpc the cumulative angular momentum is
rising. If the radial dependence alone is considered, the velocity dispersion
does not simply rise but fills an increasingly large range of values with two
well defined envelopes. The lower envelope is about constant at 200 km/s. The
upper envelope rises smoothly, joining the velocity dispersion of the outer
cluster galaxies. We interpret this behaviour as the superposition of tracer
populations with increasingly shallower radial distributions between the
extremes of the inner stellar populations and the cluster galaxies. Simple
Jeans models illustrate that a range of of mass profiles with different
anisotropies can account for all observed velocity dispersions, including
radial MOND models. Jeans models using one tracer population with a unique
density profile are not able to explain the large range of the observed
kinematics. Previous claims about the cored dark halo of NGC 3311 are therefore
probably not valid. This may in general apply to central cluster galaxies with
rising velocity dispersion profiles, where infall processes are important.Comment: 23 pages, 18 figures, accepted for publication in A&
Normocalcemic versus Hypercalcemic Primary Hyperparathyroidism: More Stone than Bone?
Introduction. Normocalcemic primary hyperparathyroidism (NPHPT) is considered a variant of the more frequent form of the disease characterized by normal serum calcium levels with high PTH. The higher prevalence of renal stones in patients with HPTP and the well established association with bone disorders show the importance of studies on how to manage asymptomatic patients. Objective. To compare the clinical and laboratory data between the normocalcemic and mild hypercalcemic forms of PHPT. Methods. We retrospectively evaluated 70 patients with PHPT, 33 normocalcemic and 37 mild hypercalcemic. Results. The frequency of nephrolithiasis was 18.2% in normocalcemic patients and 18.9% in the hypercalcemic ones (P = 0.937). Fifteen percent of normocalcemic patients had a previous history of fractures compared to 10.8% of hypercalcemic patients, although there was no statistically significant difference (P = 0.726). Conclusion. Our data confirms a high prevalence of urolithiasis in normocalcemic primary hyperparathyroidism, but with the preservation of cortical bone. This finding supports the hypothesis that this disease is not an idle condition and needs treatment
Spectral transitions in networks
We study the level spacing distribution p(s) in the spectrum of random
networks. According to our numerical results, the shape of p(s) in the
Erdos-Renyi (E-R) random graph is determined by the average degree , and
p(s) undergoes a dramatic change when is varied around the critical point
of the percolation transition, =1. When > 1, the p(s) is described by
the statistics of the Gaussian Orthogonal Ensemble (GOE), one of the major
statistical ensembles in Random Matrix Theory, whereas at =1 it follows the
Poisson level spacing distribution. Closely above the critical point, p(s) can
be described in terms of an intermediate distribution between Poisson and the
GOE, the Brody-distribution. Furthermore, below the critical point p(s) can be
given with the help of the regularised Gamma-function. Motivated by these
results, we analyse the behaviour of p(s) in real networks such as the
Internet, a word association network and a protein protein interaction network
as well. When the giant component of these networks is destroyed in a node
deletion process simulating the networks subjected to intentional attack, their
level spacing distribution undergoes a similar transition to that of the E-R
graph.Comment: 11 pages, 5 figure
Diversidade genética de famílias de seleção recorrente para resistência ao mosaico dourado em feijão preto.
O objetivo deste trabalho foi avaliar a diversidade genética entre os genitores e as famílias selecionadas no ciclo 2 (C2) utilizando marcadores microssatélites
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