instruction:
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
question:
Context: Symptomatic patients with severe aortic stenosis (AS) demonstrate abnormal left ventricular (LV) mechanics. The aim of this study was to compare mechanics in asymptomatic and symptomatic patients with severe AS using two-dimensional myocardial strain imaging.', 'One hundred fifty-four patients with severe AS (aortic valve area 1.0 cm(2)) referred to a heart valve clinic from 2004 to 2011 were studied. Thirty patients were asymptomatic, with normal LV ejection fractions ( 55%), without other significant valvular disease or wall motion abnormalities. Thirty-two symptomatic patients who underwent early aortic valve replacement, with similar age, gender, LV ejection fraction, and aortic valve area, were selected for comparison. Both groups were also compared with 32 healthy subjects with similar age and gender distributions and normal echocardiographic results who served as controls. LV longitudinal and circumferential strain and rotation were measured using speckle-tracking software applied to archived echocardiographic studies. Conventional echocardiographic and myocardial mechanical parameters were compared among the study subgroups.', 'Patients with asymptomatic severe AS demonstrated smaller reductions in longitudinal strain, higher (supernormal) apical circumferential strain (-38 6% vs -35 4%, P < .05), and extreme (supernormal) apical rotation (12.2 4.9 vs 2.9 1.7, P < .0005) compared with symptomatic patients. Apical rotation < 6 was the single significant predictor of symptoms in logistic regression analysis of clinical, echocardiographic, and mechanical parameters. Twelve asymptomatic patients underwent eventual aortic valve replacement and showed decreases in strain and apical rotation compared with baseline values.\Question: Are symptoms in severe aortic stenosis associated with decreased compensatory circumferential myocardial mechanics?
answer:
Longitudinal strain was uniformly low in patients with severe AS and lower in those with symptoms. Compensatory circumferential myocardial mechanics (increased apical circumferential strain and rotation) were absent in symptomatic patients. Thus, myocardial mechanics may help in the follow-up of patients with severe AS and timing of valve surgery.

question:
Context: Physical activity is beneficial for cancer survivors, but exercise participation is low in this population. It is therefore important to understand the psychological factors underlying exercise uptake so that more effective interventions can be developed. Social-cognitive theory constructs such as outcome expectancies predict exercise behavior, but self-report measures have several limitations. We examined the associations between implicit (automatic) cognitions and exercise behavior and self-efficacy in endometrial cancer survivors.', 'This was a longitudinal study to examine predictors of exercise behavior in female endometrial cancer survivors who all received an exercise intervention. Participants (N = 100, mean age of 57.0) completed questionnaires to assess self-report exercise-related measures (outcome expectancy and attitudes about and identification with exercise) and reaction time (RT) tasks to assess implicit exercise cognitions (expectancy accessibility, implicit attitudes about exercise, and implicit self-identification with exercise) at baseline and at 2, 4, and 6 months at follow-up. Exercise behavior was measured using accelerometers and self-report. Data were analyzed using linear mixed models.', 'Expectancy accessibility was associated with exercise duration independent of the corresponding self-report measure. Exercise implicit attitudes and self-identification were prospectively associated with exercise self-efficacy only after adjustment for the corresponding self-report measures and baseline self-efficacy. Self-report measures were also associated with study outcomes.\Question: Are self-reported and automatic cognitions associated with exercise behavior in cancer survivors?
answer:
Both self-reported cognitions and implicit cognitions may be useful to identify individuals at risk of failing to exercise. Individuals so identified might be provided with a different or more intensive intervention. The data also suggest cognitive targets for intervention. (PsycINFO Database Record

question:
Context: Although the majority of evidence does not support association between Helicobacter pylori infection and ischaemic heart disease, the nature of this relationship may differ when virulence of the infecting strains are examined.', 'The prevalence of IgG antibody evidence of infection with CagA positive stains of H. pylori was investigated in stored plasma samples from 259 cases of myocardial infarction (aged 25-70 years, 74 males) and 259 population based controls from the same area in Northern Ireland. Two-hundred and seventy (52.1%) subjects were seropositive for anti-CagA IgG. CagA seropositivity was more common in cases than in controls: 56.4 vs 47.9%, odds ratio for seropositivity in cases (95% CI) 1.41 (1.00, 1.99). Substantial attenuation of this relationship occurred on adjustment for age, sex, number of siblings, smoking and measures of socio-economic status: odds ratio (95% CI) 1.16 (0.79, 1.70). A similar pattern was seen for seropositivity for all H. pylori strains.\Question: Is infection with virulent strains of Helicobacter pylori associated with ischaemic heart disease : evidence from a population-based case-control study of myocardial infarction?
answer:
Infection with the more virulent strains of H. pylori, as with all strains, is not associated with myocardial infarction.