Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Context: Biotechnological screening processes are performed since more than 8 decades in small scale shaken bioreactors like shake flasks or microtiter plates. One of the major issues of such reactors is the sufficient oxygen supply of suspended microorganisms. Oxygen transfer into the bulk liquid can in general be increased by introducing suitable baffles at the reactor wall. However, a comprehensive and systematic characterization of baffled shaken bioreactors has never been carried out so far. Baffles often differ in number, size and shape. The exact geometry of baffles in glass lab ware like shake flasks is very difficult to reproduce from piece to piece due to the hard to control flow behavior of molten glass during manufacturing. Thus, reproducibility of the maximum oxygen transfer capacity in such baffled shake flasks is hardly given.', 'As a first step to systematically elucidate the general effect of different baffle geometries on shaken bioreactor performance, the maximum oxygen transfer capacity (OTRmax) in baffled 48-well microtiter plates as shaken model reactor was characterized. This type of bioreactor made of plastic material was chosen, as the exact geometry of the baffles can be fabricated by highly reproducible laser cutting. As a result, thirty different geometries were investigated regarding their maximum oxygen transfer capacity (OTRmax) and liquid distribution during shaking. The relative perimeter of the cross-section area as new fundamental geometric key parameter is introduced. An empirical correlation for the OTRmax as function of the relative perimeter, shaking frequency and filling volume is derived. For the first time, this correlation allows a systematic description of the maximum oxygen transfer capacity in baffled microtiter plates.
Answer: Calculated and experimentally determined OTRmax values agree within30% accuracy. Furthermore, undesired out-of-phase operating conditions can be identified by using the relative perimeter as key parameter. Finally, an optimum well geometry characterized by an increased perimeter of 10% compared to the unbaffled round geometry is identified. This study may also assist to comprehensively describe and optimize the baffles of shake flasks in future.
Is cross-section perimeter a suitable parameter to describe the effects of different baffle geometries in shaken microtiter plates?

Context: To study the prevalence and age dependency of senile plaques (SP) and neurofibrillary tangles (NFT), the brain changes characteristic of Alzheimer disease (AD), and their association with apolipoprotein E (APOE) genotypes in a community-dwelling normal population.', 'This neuropathological study used both silver staining and A beta immunohistochemistry in brain tissue microarrays, including SP coverage and NFT counts from frontal cortex and hippocampus, and APOE genotyping, and was performed on a consecutive prospective series of 603 subjects (aged between 0 and 97 years) of an unselected population living outside of institutions. Cases were subjected to autopsy following sudden or unexpected out-of-hospital death, covering 22.1% of the mortality of Tampere, Finland and its surroundings. None died of AD, although 22 (3.7%) were demented and 10 (1.7%) had memory problems.', 'Of the series, 30.8% had SP, and 42.1% had NFT; these occurred more commonly among females and showed a strong relationship with age. Both changes had already appeared at around 30 years of age, reaching an occurrence of almost 100% in the oldest. SP were more frequent in APOE epsilon 4-carriers compared with noncarriers in every age group except the oldest (>90 years). The difference was most evident during the ages 50 to 59 years, where 40.7% of epsilon 4-carriers had SP, compared with 8.2% in noncarriers (odds ratio, 8.39; 95% confidence interval, 2.55-27.62). The difference in NFT prevalence between APOE genotypes was not statistically significant in any age group.
Answer: The brain changes associated with AD may already begin developing early in middle age, especially among APOE epsilon 4 carriers.
Does apolipoprotein E-dependent accumulation of Alzheimer disease-related lesions begin in middle age?

Context: Left ventricular (LV) torsion is an important parameter of LV performance and can be influenced by several factors. Aim of this investigation was to evaluate whether QRS prolongation in left bundle branch block (LBBB) may influence global LV twist and twisting/untwisting rate in chronic systolic heart failure (HF) patients.', "We prospectively evaluated 30 healthy subjects (control group) and 100 chronic HF patients with severely impaired LV systolic function (ejection fraction 35%). Patients were divided into three groups according to QRS duration: A: QRS < 120 ms (n 49), B: 120 QRS 150 ms (n 28) and C: QRS > 150 ms (n 23). Patients in groups B and C presented LBBB. All subjects underwent standard trans-thoracic echocardiography and two-dimensional speckle-tracking echocardiography evaluation. Categorical variables were compared by the chi-square or the Fisher's exact test. Continuous variables were compared using the ANOVA test. Correlations between variables were analysed with linear regression.", 'Control subjects presented higher torsion parameters, when compared with patients in any HF group. Among the three HF groups, no differences were detected in global twist (4.79 3.54, 3.8 3.0 and 4.15 3.14 degrees, respectively), twist rate max (44.81 25.03, 37.94 19.09 and 37.61 24.49 degrees s(-1), respectively) and untwist rate max (-36.31 30.89, -27.68 34.67 and -39.62 26.27 degrees s(-1), respectively) (P>0.05 for all). At linear regression analysis, there was no relation between QRS duration and any torsion parameter (P>0.05 for all).
Answer: In patients with chronic severe systolic heart failure, QRS duration and LBBB morphology do not affect LV twisting and untwisting.
Does qRS duration in left bundle branch block affect left ventricular twisting in chronic systolic heart failure?