Publications by authors named "Bach D"

A suboptimal bias toward accepting the status quo option in decision-making is well established behaviorally, but the underlying neural mechanisms are less clear. Behavioral evidence suggests the emotion of regret is higher when errors arise from rejection rather than acceptance of a status quo option. Such asymmetry in the genesis of regret might drive the status quo bias on subsequent decisions, if indeed erroneous status quo rejections have a greater neuronal impact than erroneous status quo acceptances.

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The idea that the amygdala is crucially involved in automatically prioritising relevant events rests on evidence from a single lesion study where a patient with bilateral temporal lobe lesions, acquired in adulthood, was impaired in recall facilitation during the attentional blink. Here, in a comparable task, we show that two individuals with selective bilateral amygdala lesions retain facilitated recall of aversive words during the attentional blink. Recall facilitation was statistically significant for both patients and akin to that seen in young students and age- and education-matched controls.

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Exercise hemodynamics play an important role in the evaluation and management of patients with both severe stenotic or regurgitant valve lesions. Exercise testing in patients with valvular heart disease can help to unmask latent symptoms and define the timing of surgical intervention. Additionally, exercise-induced hemodynamics are an important tool to assess prosthetic valve function.

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Background: The St Jude Medical Epic heart valve (St Jude Medical, Inc, St Paul, Minn) is a tricomposite glutaraldehyde-preserved porcine bioprosthesis. The St Jude Medical Biocor porcine bioprosthesis is the precursor valve to the St Jude Medical Epic valve. The Epic valve is identical to the Biocor valve except that it is treated with Linx AC ethanol-based calcium mitigation therapy.

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Despite a homogenous macroscopic appearance on magnetic resonance images, subregions of the amygdala express distinct functional profiles as well as corresponding differences in connectivity. In particular, histological analysis shows stronger connections for superficial (i.e.

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Beginning in 1955, the American Heart Association recommended antibiotic prophylaxis among patients with certain structural heart diseases to decrease the likelihood of infective endocarditis (IE) following dental procedures. Over the ensuing 52 years, the American College of Cardiology/American Heart Association (ACC/AHA) guidelines were revised to address gastrointestinal and genitourinary procedures and to modify the assessment of relative risks and specific regimens for prophylaxis. Throughout the various revisions, prophylaxis was recommended for individuals who were at increased risk of developing IE based on best evidence and consensus opinion, albeit in the absence of randomized controlled trials.

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For a select number of drugs, proper management of patients includes monitoring serum or plasma concentrations of the drugs and adjusting the doses accordingly - this practice is referred to as therapeutic drug monitoring (TDM). The need for TDM arises when pharmacokinetic variability of drugs is not easily accounted for by common clinical parameters. Many chemotherapeutic drugs have large interindividual variability, yet TDM is not commonplace in chemotherapy management.

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Studies of human decision making emerge from two dominant traditions: learning theorists [1-3] study choices in which options are evaluated on the basis of experience, whereas behavioral economists and financial decision theorists study choices in which the key decision variables are explicitly stated. Growing behavioral evidence suggests that valuation based on these different classes of information involves separable mechanisms [4-8], but the relevant neuronal substrates are unknown. This is important for understanding the all-too-common situation in which choices must be made between alternatives that involve one or another kind of information.

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Regret-related brain activity is dependent on free choice, but it is unclear whether this activity is a function of more subtle differences in the degree of responsibility a decision-maker exerts over a regrettable outcome. In this experiment, we show that trial-by-trial subjective ratings of regret depend on a higher subjective sense of responsibility, as well as being dependent on objective responsibility. Using fMRI we show an enhanced amygdala response to regret-related outcomes when these outcomes are associated with high, as compared to low, responsibility.

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The opinions of others can easily affect how much we value things. We investigated what happens in our brain when we agree with others about the value of an object and whether or not there is evidence, at the neural level, for social conformity through which we change object valuation. Using functional magnetic resonance imaging we independently modeled (1) learning reviewer opinions about a piece of music, (2) reward value while receiving a token for that music, and (3) their interaction in 28 healthy adults.

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Anticipatory skin conductance responses [SCRs] are a widely used measure of aversive conditioning in humans. Here, we describe a dynamic causal model [DCM] of how anticipatory, evoked, and spontaneous skin conductance changes are generated by sudomotor nerve activity. Inversion of this model, using variational Bayes, provides a means of inferring the most likely sympathetic nerve activity, given observed skin conductance responses.

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Spontaneous fluctuations (SF) in skin conductance are often used to index sympathetic arousal and emotional states. SF are caused by sudomotor nerve activity (SNA), which is a direct indicator of sympathetic arousal. Here, we describe a dynamic causal model (DCM) of how SNA causes SF, and apply variational Bayesian model inversion to infer SNA, given empirically observed SF.

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"Regret aversion" is proposed to explain a tendency to avoid future choices that have induced past regret. However, regret might also motivate us to repeat previous regret-related choices to make up for their previous selection, a behavior resembling "chasing" in the context of gambling. In the current experiment, we acquired fMRI brain data while participants placed monetary bets on repeated gambles.

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Echocardiography/Doppler is the standard clinical tool for the assessment of hemodynamics after aortic valve replacement. Analysis can include mean and peak transvalvular gradients, dimensionless valve index, effective orifice area from the continuity equation, geometric orifice area from planimetry, and energy loss coefficient. High gradients after aortic valve replacement can be, but are not necessarily, caused by left ventricular outflow obstruction; and not all left ventricular outflow obstruction after aortic valve replacement is due to prosthesis dysfunction.

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Introduction: Mild unconjugated hyperbilirubinemia seems to be more common in patients with disorders from the schizophrenic spectrum than in other psychiatric patients or in the general population and has been linked to brain alterations. This spectrum however contains a number of diagnostic entities that might not share the same etiological and environmental factors.

Methods: 325 hospital admissions were analysed over a one-year period.

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Autonomic arousal is often indexed by spontaneous fluctuations in skin conductance. Here, we derive a simple measure of sympathetic arousal, using a convolution model of how sudomotor bursting causes fluctuations in skin conductivity. Under this model, the time-integral of measured conductance is proportional to the frequency and amplitude of sudomotor bursts.

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Until the last decade, acquired pulmonary vein (PV) stenosis in the adult population was a rare finding, caused by neoplasm or inflammatory conditions such as sarcoidosis or fibrosing mediastinitis. With the increased use of catheter-based ablation for the treatment of atrial fibrillation, PV stenosis is increasingly recognized as a complication of this procedure. Additionally, PV stenosis has been described as a rare complication of cardiac surgery.

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Analytic tools for psychophysiological signals often make implicit assumptions that are unspecified. In developing a mathematical framework for analysis of skin conductance responses [SCRs], we formalise our assumptions by positing that SCRs can be regarded as the output of a linear time-invariant filter. Here, we provide an empirical test of these assumptions.

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Background: Some patients with severe symptomatic aortic stenosis (AS) do not undergo aortic valve replacement (AVR) despite demonstrated symptomatic and survival advantages and despite unequivocal guideline recommendations for surgical evaluation.

Methods And Results: In 3 large tertiary care institutions (university, Veterans Affairs, and private practice) in Washtenaw County, Mich, patients were identified with unrefuted echocardiography/Doppler evidence of severe AS during calendar year 2005. Medical records were retrospectively reviewed for symptoms, referral for AVR, calculated operative risk for AVR, and rationale as to why patients did not undergo valve replacement.

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A comprehensive electron energy-loss spectroscopy study of niobium (Nb) and stable Nb-oxide phases (NbO, NbO2, Nb2O5) was carried out. In this work (Part I), the plasmons and energy-loss near-edge structures (ELNES) of all relevant Nb edges (Nb-N2,3, Nb-M4,5, Nb-M2,3, Nb-M1, and Nb-L2,3) up to energy losses of about 2600 eV and the O-K edge are analyzed with respect to achieving characteristic fingerprints of Nb in different formal oxidation states (0 for metallic Nb, +2 for NbO, +4 for NbO2, and +5 for Nb2O5). Chemical shifts of the Nb-N2,3, Nb-M4,5, Nb-M2,3, and Nb-L2,3 edges are extracted from the spectra that amount to about 4 eV as the oxidation state increases from 0 for Nb to +5 for Nb2O5.

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A comprehensive electron energy-loss spectroscopy (EELS) study of niobium (Nb) and stable Nb-oxide phases (NbO, NbO2, Nb2O5) was carried out. Part II of this work is devoted to quantitative EELS by means of experimental k-factors derived from the intensity ratio of the O-K edge and the Nb-M4,5 or Nb-M2,3 edges for all three stable Nb-oxides. The precision and accuracy of the quantification are investigated with respect to the influence of intensity-measurement energy windows, background subtraction, and sample thickness.

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Objective: The purpose of our study was to determine whether CT can accurately evaluate mechanical heart valve size and function.

Materials And Methods: Sixty-two patients with mechanical valves (37 single-disc, 27 bileaflet; 59 aortic, 5 mitral) were evaluated with ECG-gated 64-MDCT and transthoracic echocardiography; a subset of 10 patients underwent cinefluoroscopy. Two readers independently interpreted each study.

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This study investigated the acute pharmacodynamic effects of sildenafil in patients with pulmonary arterial hypertension (PAH) and concomitant bosentan treatment, in view of a mutual pharmacokinetic interaction between the 2 drugs. This prospective, open-label, noncomparative, multicenter, phase II study enrolled 45 patients (>or=18 years) with stable PAH (idiopathic, familial, or related to corrected congenital systemic-to-pulmonary shunts, drugs, or toxins) and on bosentan treatment for at least 3 months. Patients underwent right heart catheterization to evaluate the acute hemodynamic effects of (a) inhaled nitric oxide (iNO) and (b) a single oral dose of sildenafil (25 mg).

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