5,818 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
Subtleties on energy calculations in the image method
In this pedagogical work we point out a subtle mistake that can be done by
undergraduate or graduate students in the computation of the electrostatic
energy of a system containing charges and perfect conductors if they naively
use the image method. Specifically, we show that the naive expressions for the
electrostatic energy for these systems obtained directly from the image method
are wrong by a factor 1/2. We start our discussion with well known examples,
namely, point charge-perfectly conducting wall and point charge-perfectly
conducting sphere and then proceed to the demonstration of general results,
valid for conductors of arbitrary shapes.Comment: 9 pages, 2 figures; Major change in this version: subsection added to
Sect.4 (theorem generalization). Minor changes: title replaced; corrections
to the English; some explanatory comments adde
Coherence Temperature in the Diluted Periodic Anderson Model
The Kondo and Periodic Anderson Model (PAM) are known to provide a
microscopic picture of many of the fundamental properties of heavy fermion
materials and, more generally, a variety of strong correlation phenomena in
and systems. In this paper, we apply the Determinant Quantum Monte
Carlo (DQMC) method to include disorder in the PAM, specifically the removal of
a fraction of the localized orbitals. We determine the evolution of the
coherence temperature , where the local moments and conduction electrons
become entwined in a heavy fermion fluid, with and with the hybridization
between localized and conduction orbitals. We recover several of the
principal observed trends in of doped heavy fermions, and also show that,
within this theoretical framework, the calculated Nuclear Magnetic Resonance
(NMR) relaxation rate tracks the experimentally measured behavior in pure and
doped CeCoIn. Our results contribute to important issues in the
interpretation of local probes of disordered, strongly correlated systems.Comment: 8 pages, 4 figure
Volatile compounds contribution of Hanseniaspora guilliermondii and Hanseniaspora uvarum during red wine vinifications
This work aims to investigate the contribution of a selected non-Saccharomyces yeast species, Hanseniaspora
guilliermondii, to higher alcohols, esters, fatty acids and heavy sulphur compounds composition
of red wine. Red grape must vinifications of 100 l were performed and an inoculated fermentation with
H. guilliermondii was compared to a spontaneous fermentation. The presence of apiculate yeasts was
observed in both fermentations; however, Hanseniaspora uvarum was the only apiculate yeast isolated
from the spontaneous fermentation. Apiculate yeasts dominated the fermentation until an ethanol
concentration of 6% (v/v) was attained and remained in considerable high levels for an ethanol
concentration of 12.5% (v/v). The grape must inoculated with H. guilliermondii led to the production of
wine with higher concentrations of 1-propanol, 2-phenylethyl acetate and 3-(methylthio)propionic acid,
and lower amounts of ethyl hexanoate, pentanoic acid, free fatty acids, 2-methyltetrahydrothiophen-3-
one and acetic acid-3-(methylthio)propyl ester, than wine resulting from the spontaneous fermentation.
The present study shows that the use of specific apiculate yeasts in grape must fermentations may lead to
the production of wines with different chemical profiles, emphasising the importance of Hanseniaspora
yeasts as mixed starter cultures with Saccharomyces cerevisiae, in winemaking.info:eu-repo/semantics/acceptedVersio
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