1,693 research outputs found
Expectancy changes the self-monitoring of voice identity
Selfâvoice attribution can become difficult when voice characteristics are ambiguous, but functional magnetic resonance imaging (fMRI) investigations of such ambiguity are sparse. We utilized voiceâmorphing (selfâother) to manipulate (unâ)certainty in selfâvoice attribution in a buttonâpress paradigm. This allowed investigating how levels of selfâvoice certainty alter brain activation in brain regions monitoring voice identity and unexpected changes in voice playback quality. FMRI results confirmed a selfâvoice suppression effect in the right anterior superior temporal gyrus (aSTG) when selfâvoice attribution was unambiguous. Although the right inferior frontal gyrus (IFG) was more active during a selfâgenerated compared to a passivelyâheard voice, the putative role of this region in detecting unexpected selfâvoice changes during action was demonstrated only when hearing the voice of another speaker and not when attribution was uncertain. Further research on the link between right aSTG and IFG is required and may establish a threshold monitoring voice identity in action. The current results have implications for a better understanding of the altered experience of selfâvoice feedback in auditory verbal hallucinations
Conflicts of Interest in the Underwriting of IPOs and Price Stabilization
Banks that supply capital and simultaneously underwrite securities for the same clients may benefit themselves or their clients at the expenses of investors by overpricing securities. We investigate this issue by analyzing price stabilization and short-term returns of IPOs. Our analysis suggests that equity-conflicted underwriters overprice IPOs and use price stabilization to disguise overpricing. The same does not happen with loan conflicted underwriters. We also show that the partial adjustment phenomenon may result from price stabilization, since it disappears after the stabilization is over.N/
Buttressing staples with cholecyst-derived extracellular matrix (CEM) reinforces staple lines in an ex vivo peristaltic inflation model
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ Springer Science + Business Media, LLC 2008Background - Staple line leakage and bleeding are the most common problems associated with the use of surgical staplers for gastrointestinal resection and anastomotic procedures. These complications can be reduced by reinforcing the staple lines with buttressing materials. The current study reports the potential use of cholecyst-derived extracellular matrix (CEM) in non-crosslinked (NCEM) and crosslinked (XCEM) forms, and compares their mechanical performance with clinically available buttress materials [small intestinal submucosa (SIS) and bovine pericardium (BP)] in an ex vivo small intestine model.
Methods - Three crosslinked CEM variants (XCEM0005, XCEM001, and XCEM0033) with different degree of crosslinking were produced. An ex vivo peristaltic inflation model was established. Porcine small intestine segments were stapled on one end, using buttressed or non-buttressed surgical staplers. The opened, non-stapled ends were connected to a peristaltic pump and pressure transducer and sealed. The staple lines were then exposed to increased intraluminal pressure in a peristaltic manner. Both the leak and burst pressures of the test specimens were recorded.
Results - The leak pressures observed for non-crosslinked NCEM (137.8â±â22.3 mmHg), crosslinked XCEM0005 (109.1â±â14.1 mmHg), XCEM001 (150.1â±â16.0 mmHg), XCEM0033 (98.8â±â10.5 mmHg) reinforced staple lines were significantly higher when compared to non-buttressed control (28.3â±â10.8 mmHg) and SIS (one and four layers) (62.6â±â11.8 and 57.6â±â12.3 mmHg, respectively) buttressed staple lines. NCEM and XCEM were comparable to that observed for BP buttressed staple lines (138.8â±â3.6 mmHg). Only specimens with reinforced staple lines were able to achieve high intraluminal pressures (ruptured at the intestinal mesentery), indicating that buttress reinforcements were able to withstand pressure higher than that of natural tissue (physiological failure).
Conclusions - These findings suggest that the use of CEM and XCEM as buttressing materials is associated with reinforced staple lines and increased leak pressures when compared to non-buttressed staple lines. CEM and XCEM were found to perform comparably with clinically available buttress materials in this ex vivo model.Enterprise Irelan
A Variational Method in Out of Equilibrium Physical Systems
A variational principle is further developed for out of equilibrium dynamical
systems by using the concept of maximum entropy. With this new formulation it
is obtained a set of two first-order differential equations, revealing the same
formal symplectic structure shared by classical mechanics, fluid mechanics and
thermodynamics. In particular, it is obtained an extended equation of motion
for a rotating dynamical system, from where it emerges a kind of topological
torsion current of the form , with and
denoting components of the vector potential (gravitational or/and
electromagnetic) and is the angular velocity of the accelerated frame.
In addition, it is derived a special form of Umov-Poynting's theorem for
rotating gravito-electromagnetic systems, and obtained a general condition of
equilibrium for a rotating plasma. The variational method is then applied to
clarify the working mechanism of some particular devices, such as the Bennett
pinch and vacuum arcs, to calculate the power extraction from an hurricane, and
to discuss the effect of transport angular momentum on the radiactive heating
of planetary atmospheres. This development is seen to be advantageous and opens
options for systematic improvements.Comment: 22 pages, 1 figure, submitted to review, added one referenc
The role of the cerebellum in adaptation: ALE meta-analyses on sensory feedback error
It is widely accepted that unexpected sensory consequences of self-action engage the
cerebellum. However, we currently lack consensus on where in the cerebellum, we find
fine-grained differentiation to unexpected sensory feedback. This may result from
methodological diversity in task-based human neuroimaging studies that experimentally alter the quality of self-generated sensory feedback. We gathered existing studies
that manipulated sensory feedback using a variety of methodological approaches and
performed activation likelihood estimation (ALE) meta-analyses. Only half of these
studies reported cerebellar activation with considerable variation in spatial location.
Consequently, ALE analyses did not reveal significantly increased likelihood of activation in the cerebellum despite the broad scientific consensus of the cerebellum's
involvement. In light of the high degree of methodological variability in published studies, we tested for statistical dependence between methodological factors that varied
across the published studies. Experiments that elicited an adaptive response to continuously altered sensory feedback more frequently reported activation in the cerebellum
than those experiments that did not induce adaptation. These findings may explain the
surprisingly low rate of significant cerebellar activation across brain imaging studies
investigating unexpected sensory feedback. Furthermore, limitations of functional
magnetic resonance imaging to probe the cerebellum could play a role as climbing fiber
activity associated with feedback error processing may not be captured by it. We provide methodological recommendations that may guide future studies
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