In situ aortic root in vitro testing of the stented and stenless porcine aortic heart valves

Background - The stent, Delrin® support frame, for porcine heart valves has been blamed for reduced durability of these valves due to the additional stress caused by the relative stiffness of the stent. There is a tendency among surgeons to do away with the stent in the aortic position and use porcine stentless valves which are sewn directly in the aortic position after removing diseased valve. These stentless valves are extremely difficult to test and no appropriate holder has been designed for this purpose. New approach for in vitro testing of these valves has been developed at Sheihigh, Inc., Millburn NJ. The stentless valves are sewn in real porcine heart; the aortic root is dissected out and the aortic root is connected to a holder then inserted in the Pulse Duplicator System. This aortic root is kept fresh with antiseptic solutions but not fixed with glutaraldehyde since it can become stiffer than the natural aorta. Method - In vitro hemodynamics, blood flow performance, of porcine bioprostheses were tested under physiological conditions using the pulse duplicator system. The system is comprised of a test chamber in which the porcine bioprosthesis is inserted, a pressure transducer, a flow probe, an amplifier pair, and real time software to analyze the fluid dynamics of stented and unstented porcine bioprostheses. Thirteen Shethigh Porcine valves were tested in the Pulse Duplicator System for this study which include 7 - 25mm valve, 4 stented and 3 stentless, and 6 - 23mm valves, 3 stented and 3 stentless. Results - Preliminary results from testing three of each stented and stentless 23mm valves at a rate of approximately 90 Beats Per Minute (BPM) showed an average of a 6% increase in the Effective Orifice Area (EOA) of the Stentless bioprosthesis over the standard Stented bioprosthesis. The EOA ranged from a high of 2.41cm2 for the 25mm stentless to a low of 21 8cm2 for the 25mm stented bioprosthesis. The mean EOA for the stented bioprostheses was 1.94cm2 and 2.06cm2 for the stentless bioprostheses. Conclusion - The series of tests which were performed using aortic roots and sizers to size the aortic root to implant the valve into the proper size root revealed that sizing the root is critical when trying to achieve a maximum Effective Orifice Area. Sizing of the stented valve implanted is not as critical due to the stent providing a predefined area for the valve, but then there is no means for the valve to distend at high flow rates. The stentless bioprosthesis is superior to the standard bioprosthesis in the sense there is no stress on the valve comparable to the stented bioprosthesis. At high flow rates the EOA of the stentless valve is not limited to the inside diameter of the valve because it is allowed to distend outward at times of high flow rates. Using stentless valves is of importance at times of high flow rates in order to eliminate the stenosis, the abnormal narrowing of the orifice, opening, in a heart valve, which is produced in stented valves

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Autonomy versus futility? Barriers to good clinical practice in end-of-life care: a Queensland case

Findings from a Queensland coronial inquest highlight the complex clinical, ethical and legal issues that arise in end-of-life care when clinicians and family members disagree about a diagnosis of clinical futility. The tension between the law and best medical practice is highlighted in this case, as doctors are compelled to seek family consent to not commence a futile intervention. Good communication between doctors and families, as well as community and professional education, is essential to resolve tensions that can arise when there is disagreement about treatment at the end of life

Psychological profile of individuals presenting with chronic cough

Chronic refractory cough (CRC) is a common problem in respiratory clinics. Adverse effects on quality of life are documented in the literature, but relatively little is known about the underlying psychological factors in this patient population. We aimed to investigate the association of psychological factors with chronic cough, comparing CRC to explained cough and non-cough groups. 67 patients attending a specialist cough clinic (CRC, n=25; explained cough, n=42) and 22 non-cough individuals participated. All participants completed the Hospital Anxiety & Depression Scale, Big Five Inventory (Personality), Chalder Fatigue Scale and Patient Health Questionnaire-15. Cough patients also completed the Illness Perception Questionnaire-Revised. Appropriate statistical analyses were used to compare participant groups. Chronic refractory coughers displayed significantly higher levels of anxiety, depression, fatigue and somatic physical symptoms than non-cough participants. Compared to explained coughers, there were higher depression and fatigue scores and significantly more negative illness representations (specifically, strong beliefs regarding negative consequences, lower illness coherence and higher emotional representations). “Explained” coughers reported significantly increased fatigue and somatic symptoms in comparison to non-coughers. The prevalence of fatigue, low mood, negative illness beliefs and increased physical symptom reporting should be considered in consultations and in developing novel interventions for CRC patients

Wind-Tunnel Balance Characterization for Hypersonic Research Applications

Wind-tunnel research was recently conducted at the NASA Langley Research Center s 31-Inch Mach 10 Hypersonic Facility in support of the Mars Science Laboratory s aerodynamic program. Researchers were interested in understanding the interaction between the freestream flow and the reaction control system onboard the entry vehicle. A five-component balance, designed for hypersonic testing with pressurized flow-through capability, was used. In addition to the aerodynamic forces, the balance was exposed to both thermal gradients and varying internal cavity pressures. Historically, the effect of these environmental conditions on the response of the balance have not been fully characterized due to the limitations in the calibration facilities. Through statistical design of experiments, thermal and pressure effects were strategically and efficiently integrated into the calibration of the balance. As a result of this new approach, researchers were able to use the balance continuously throughout the wide range of temperatures and pressures and obtain real-time results. Although this work focused on a specific application, the methodology shown can be applied more generally to any force measurement system calibration

Calibration Modeling Methodology to Optimize Performance for Low Range Applications

Calibration is a vital process in characterizing the performance of an instrument in an application environment and seeks to obtain acceptable accuracy over the entire design range. Often, project requirements specify a maximum total measurement uncertainty, expressed as a percent of full-scale. However in some applications, we seek to obtain enhanced performance at the low range, therefore expressing the accuracy as a percent of reading should be considered as a modeling strategy. For example, it is common to desire to use a force balance in multiple facilities or regimes, often well below its designed full-scale capacity. This paper presents a general statistical methodology for optimizing calibration mathematical models based on a percent of reading accuracy requirement, which has broad application in all types of transducer applications where low range performance is required. A case study illustrates the proposed methodology for the Mars Entry Atmospheric Data System that employs seven strain-gage based pressure transducers mounted on the heatshield of the Mars Science Laboratory mission

Tube-side mass transfer for hollow fibre membrane contactors operated in the low Graetz range

Transformation of the tube-side mass transfer coefficient derived in hollow fibre membrane contactors (HFMC) of different characteristic length scales (equivalent diameter and fibre length) has been studied when operated in the low Graetz range (Gz < 10). Within the low Gz range, mass transfer is generally described by the Graetz problem (Sh=3.67) which assumes that the concentration profile comprises a constant shape over the fibre radius. In this study, it is experimentally evidenced that this assumption over predicts mass transfer within the low Graetz range. Furthermore, within the low Gz range (below 2), a proportional relationship between the experimentally determined mass transfer coefficient (Kov) and the Graetz number has been identified. For Gz numbers below 2, the experimental Sh number approached unity, which suggests that mass transfer is strongly dependent upon diffusion. However, within this diffusion controlled region of mass transfer, tube-side fluid velocity remained important. For Gz numbers above 2, Sh could be satisfactorily described by extension to the Lévêque solution, which can be ascribed to the constrained growth of the concentration boundary layer adjacent to the fibre wall. Importantly this study demonstrates that whilst mass transfer in the low Graetz range does not explicitly conform to either the Graetz problem or classical Lévêque solution, it is possible to transform the experimentally derived overall mass transfer coefficient (Kov) between characteristic length scales (dh and L). This was corroborated by comparison of the empirical relationship determined in this study (Sh=0.36Gz) with previously published studies operated in the low Gz range. This analysis provides important insight for process design when slow tube-side flows, or low Schmidt numbers (coincident with gases) constrain operation of hollow fibre membrane contactors to the low Gz range

School-Based Data Teams Ask the Darnedest Questions About Statistics: Three Essays in the Epistemology of Statistical Consulting and Teaching

The essays in this thesis attempt to answer the most difficult questions that I have faced as a teacher and consultant for school-based data teams. When we report statistics to our fellow educators, what do we say and what do we leave unsaid? What do averages mean when no student is average? Why do we treat our population of students as infinite when we test for statistical significance? I treat these as important philosophical questions. In the first essay, I use Paul Grice’s philosophical analysis of conversational logic to understand how data teams can accidentally mislead with true statistics, and I use Bernard Williams’s philosophical analysis of truthfulness to understand the value, for data teams, of not misleading with statistics. In short, statistical reports can be misleading when they violate the Gricean maxims of conversation (e.g., “be relevant,” “be orderly”). I argue that, for data teams, adhering to the Gricean maxims is an intrinsic value, alongside Williams’s intrinsic values of Sincerity and Accuracy. I conclude with some recommendations for school-based data teams. In the second essay, I build on Nelson Goodman and Catherine Z. Elgin’s analyses of exemplification to argue that averages (i.e., medians and means) are attenuated, moderate, and sometimes fictive exemplars. As such, medians and means lend themselves to scientific objectivity. In the third essay, I use Goodman’s theory of counterfactuals and Carl Hempel’s theory of explanation to articulate why data teams should make statistical inferences to infinite populations that include possible but not actual students. Data teams are generally concerned that their results are explainable by random chance. Random chance, as an explanation, implies lawlike generalizations, which in turn imply counterfactual claims about possible but not actual subjects. By statistically inferring to an infinite population of students, data teams can evaluate those counterfactual claims in order to assess the plausibility of random chance as an explanation for their findings

Effect of a Commercially Available Low-Dose Capsaicin Supplement on Knee Extensor Contractile Function

International Journal of Exercise Science 13(2): 312-318, 2020. Capsaicin, the active pungent ingredient in chili peppers and various spicy foods, is demonstrated to influence a variety of physiological systems including skeletal muscle. The purpose of this study was to examine if a chewable capsaicin supplement (1.2 mg) could enhance isokinetic knee extensor contractile performance. Nine young, recreationally active individuals (5 females/4 males; 23.6 ± 1.5 yrs; 24.2 ± 3.3 kg/m2) participated in this randomized, single-blind crossover study. Following a familiarization session, participants completed two isokinetic knee extensor contractile function assessments, 45 minutes after ingesting either a capsaicin fruit gummy or eucaloric placebo, the order of which was randomized. Knee extensor peak torque (strength), summed torque (endurance) and fatigue index (fatigue) were compared between trials. Knee extensor peak torque was significantly greater (p \u3c 0.05; d= 0.80) in the capsaicin (126.0 ± 40.4 N⋅m-1) than the placebo (118.8 ± 41.3 N⋅m-1) trial. No significant differences (p \u3e 0.05) were found for summed torque (8012 ± 2771 vs. 7823 ± 2611 N⋅m-1; d= 0.45) or fatigue index (56.0 ± 17.1 vs. 48.7 ± 21.0 %; d= 0.46) between capsaicin and placebo trials, respectively. These findings, in a relatively modest and mixed-gender sample, suggest that pre-exercise capsaicin ingestion may benefit knee extensor muscle strength but does not appear to affect parameters of skeletal muscle endurance or fatigue

The GEEC2 spectroscopic survey of Galaxy Groups at 0.8<z<10.8<z<1

We present the data release of the Gemini-South GMOS spectroscopy in the fields of 11 galaxy groups at $0.8<z<1$, within the COSMOS field. This forms the basis of the Galaxy Environment Evolution Collaboration 2 (GEEC2) project to study galaxy evolution in haloes with $M\sim 10^{13}M_\odot$ across cosmic time. The final sample includes $162$ spectroscopically--confirmed members with $R50$ per cent complete for galaxies within the virial radius, and with stellar mass $M_{\rm star}>10^{10.3}M_\odot$. Including galaxies with photometric redshifts we have an effective sample size of $\sim 400$ galaxies within the virial radii of these groups. We present group velocity dispersions, dynamical and stellar masses. Combining with the GCLASS sample of more massive clusters at the same redshift we find the total stellar mass is strongly correlated with the dynamical mass, with $\log{M_{200}}=1.20\left(\log{M_{\rm star}}-12\right)+14.07$. This stellar fraction of $~\sim 1$ per cent is lower than predicted by some halo occupation distribution models, though the weak dependence on halo mass is in good agreement. Most groups have an easily identifiable most massive galaxy (MMG) near the centre of the galaxy distribution, and we present the spectroscopic properties and surface brightness fits to these galaxies. The total stellar mass distribution in the groups, excluding the MMG, compares well with an NFW profile with concentration $4$, for galaxies beyond $\sim 0.2R_{200}$. This is more concentrated than the number density distribution, demonstrating that there is some mass segregation.Comment: Accepted for publication in MNRAS. The appendix is omitted due to large figures. The full version will be available from the MNRAS website and from http://quixote.uwaterloo.ca/~mbalogh/papers/GEEC2_data.pdf. Long data tables are available from MNRAS or by contacting the first autho