STME Hydrogen Mixer Study

The hydrogen mixer for the Space Transportation Main Engine is used to mix cold hydrogen bypass flow with warm hydrogen coolant chamber gas, which is then fed to the injectors. It is very important to have a uniform fuel temperature at the injectors in order to minimize mixture ratio problems due to the fuel density variations. In addition, the fuel at the injector has certain total pressure requirements. In order to achieve these objectives, the hydrogen mixer must provide a thoroughly mixed fluid with a minimum pressure loss. The AEROVISC computational fluid dynamics (CFD) code was used to analyze the STME hydrogen mixer, and proved to be an effective tool in optimizing the mixer design. AEROVISC, which solves the Reynolds Stress-Averaged Navier-Stokes equations in primitive variable form, was used to assess the effectiveness of different mixer designs. Through a parametric study of mixer design variables, an optimal design was selected which minimized mixed fuel temperature variation and fuel mixer pressure loss. The use of CFD in the design process of the STME hydrogen mixer was effective in achieving an optimal mixer design while reducing the amount of hardware testing

What’s Wrong with Digital Stewardship: Evaluating the Organization of Digital Preservation Programs from Practitioners’ Perspectives

The National Digital Stewardship Alliance surveyed practitioners in 2012 and again in 2017 to gauge, among other things, how satisfied they were with their organizations’ digital preservation function. This study seeks to understand what causes the high and rising levels of dissatisfaction that practitioners reported. We interviewed 21 digital stewards and asked them to describe the organizational context in which they work; to reflect on what aspects of their organizations’ approach to digital preservation are working well and which are not; and to evaluate necessary areas of improvement. We identified experiences that were common among participants using a qualitative research methodology based on phenomenology. These conversations revealed that practitioners largely consider digital stewardship values and goals to be misunderstood at an organizational level, and demonstrated that the absence of a long-term vision for digital stewardship disempowers practitioners

The Small Scale Anisotropies, the Spectrum and the Sources of Ultra High Energy Cosmic Rays

We calculate the number density and luminosity of the sources of ultra high energy cosmic rays (UHECRs), using the information about the small scale anisotropies and the observed spectra. We find that the number of doublets and triplets observed by AGASA can be best reproduced for a source density of $\sim 10^{-5} Mpc^{-3}$, with large uncertainties. The spectrum of UHECRs implies an energy input of $\sim 6\times 10^{44} erg yr^{-1} Mpc^{-3}$ above $10^{19}$ eV and an injection spectrum $\propto E^{-2.6}$. A flatter injection spectrum, $E^{-2.4}$, can be adopted if the sources have luminosity evolution $\propto (1+z)^4$. The combination of these two pieces of information suggests that the single sources should on average have a cosmic ray luminosity above $10^{19}$ eV of $L_{source}\approx 2\times 10^{42} erg s^{-1}$, weakly dependent upon the injection spectrum. Unfortunately, with the limited statistics of events available at present, there are approximately one-two orders of magnitude uncertainty in the source density provided above. We make predictions on the expected performances of the Auger and EUSO experiments, with particular attention for the expected improvements in our understanding of the nature of the sources of UHECRs. We find that a critical experimental exposure $\Sigma_c$ exists, such that experiments with exposure larger than $\Sigma_c$ can detect at least one event from each source at energies above $10^{20}$ eV. This represents a unique opportunity to directly count and identify the sources of UHECRs.Comment: Submitted to Astropart. Phy

Study protocol: NITric oxide during cardiopulmonary bypass to improve Recovery in Infants with Congenital heart defects (NITRIC trial): a randomised controlled trial

Introduction Congenital heart disease (CHD) is a major cause of infant mortality. Many infants with CHD require corrective surgery with most operations requiring cardiopulmonary bypass (CPB). CPB triggers a systemic inflammatory response which is associated with low cardiac output syndrome (LCOS), postoperative morbidity and mortality. Delivery of nitric oxide (NO) into CPB circuits can provide myocardial protection and reduce bypass-induced inflammation, leading to less LCOS and improved recovery. We hypothesised that using NO during CPB increases ventilator-free days (VFD) (the number of days patients spend alive and free from invasive mechanical ventilation up until day 28) compared with standard care. Here, we describe the NITRIC trial protocol. Methods and analysis The NITRIC trial is a randomised, double-blind, controlled, parallel-group, two-sided superiority trial to be conducted in six paediatric cardiac surgical centres. One thousand three-hundred and twenty infants <2 years of age undergoing cardiac surgery with CPB will be randomly assigned to NO at 20 ppm administered into the CPB oxygenator for the duration of CPB or standard care (no NO) in a 1:1 ratio with stratification by age (<6 and ≥6 weeks), single ventricle physiology (Y/N) and study centre. The primary outcome will be VFD to day 28. Secondary outcomes include a composite of LCOS, need for extracorporeal membrane oxygenation or death within 28 days of surgery; length of stay in intensive care and in hospital; and, healthcare costs. Analyses will be conducted on an intention-to-treat basis. Preplanned secondary analyses will investigate the impact of NO on host inflammatory profiles postsurgery. Ethics and dissemination The study has ethical approval (HREC/17/QRCH/43, dated 26 April 2017), is registered in the Australian New Zealand Clinical Trials Registry (ACTRN12617000821392) and commenced recruitment in July 2017. The primary manuscript will be submitted for publication in a peer-reviewed journal. Trial registration number ACTRN12617000821392.</p

Floating Hem-o-Lok Clips in the Bladder without Stone Formation after Robot-Assisted Laparoscopic Radical Prostatectomy

Hem-o-Lok clips (Weck Surgical Instruments, Teleflex Medical, Durham, NC, USA) are widely used in robot-assisted laparoscopic radical prostatectomy because of their easy application and secure clamping. To date, there have been some reports of intravesical migration of these clips causing urethral erosion, bladder neck contractures, and subsequent calculus formation. We report the first case of bladder migration of Hem-o-Lok clips without stone formation after robot-assisted laparoscopic radical prostatectomy. The Hem-o-Lok clips were found during urethral dilation with a guide wire for bladder neck contracture under cystourethroscopy. The Hem-o-Lok clips were floating in the bladder without stone formation and were removed by a cystoscopic procedure

Clusters of microRNAs emerge by new hairpins in existing transcripts

Genetic linkage may result in the expression of multiple products from a polycistronic transcript, under the control of a single promoter. In animals, protein-coding polycistronic transcripts are rare. However, microRNAs are frequently clustered in the genomes of animals, and these clusters are often transcribed as a single unit. The evolution of microRNA clusters has been the subject of much speculation, and a selective advantage of clusters of functionally related microRNAs is often proposed. However, the origin of microRNA clusters has not been so far explored. Here, we study the evolution of microRNA clusters in Drosophila melanogaster. We observed that the majority of microRNA clusters arose by the de novo formation of new microRNA-like hairpins in existing microRNA transcripts. Some clusters also emerged by tandem duplication of a single microRNA. Comparative genomics show that these clusters are unlikely to split or undergo rearrangements. We did not find any instances of clusters appearing by rearrangement of pre-existing microRNA genes. We propose a model for microRNA cluster evolution in which selection over one of the microRNAs in the cluster interferes with the evolution of the other linked microRNAs. Our analysis suggests that the study of microRNAs and small RNAs must consider linkage associations

Flashing a smile: Startle eyeblink modulation by masked affective faces

Affective faces are important stimuli with relevance to healthy and abnormal social and affective information processing. The aim of this study was to investigate the effect of brief presentations of affective faces on attention and emotional state across the time course of stimulus processing, as indexed by startle eyeblink response modulation. Healthy adults were presented with happy, neutral, and disgusted male and female faces that were backward masked by neutral faces. Startle responses were elicited at 300, 800, and 3,500 ms following stimulus presentation to probe early and late startle eyeblink modulation, indicative of attention allocation and emotional state, respectively. Results revealed that, at 300 ms, both face expression and face gender modulated startle eyeblink response, suggesting that more attention was allocated to masked happy compared to disgusted female faces, and masked disgusted compared to neutral male faces. There were no effects of either face expression or face gender on startle modulation at 800 ms. At 3,500 ms, target face expression did not modulate startle, but male faces elicited larger startle responses than female faces, indicative of a more negative emotional state. These findings provide a systematic investigation of attention and emotion modulation by brief affective faces across the time course of stimulus processing.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142906/1/psyp13012_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142906/2/psyp13012.pd

The association of clinical indication for exercise stress testing with all-cause mortality: the FIT Project

INTRODUCTION: We hypothesized that the indication for stress testing provided by the referring physician would be an independent predictor of all-cause mortality. MATERIAL AND METHODS: We studied 48,914 patients from The Henry Ford Exercise Testing Project (The FIT Project) without known congestive heart failure who were referred for a clinical treadmill stress test and followed for 11 ±4.7 years. The reason for stress test referral was abstracted from the clinical test order, and should be considered the primary concerning symptom or indication as stated by the ordering clinician. Hierarchical multivariable Cox proportional hazards regression was performed, after controlling for potential confounders including demographics, risk factors, and medication use as well as additional adjustment for exercise capacity in the final model. RESULTS: A total of 67% of the patients were referred for chest pain, 12% for shortness of breath (SOB), 4% for palpitations, 3% for pre-operative evaluation, 6% for abnormal prior testing, and 7% for risk factors only. There were 6,211 total deaths during follow-up. Compared to chest pain, those referred for palpitations (HR = 0.72, 95% CI: 0.60-0.86) and risk factors only (HR = 0.72, 95% CI: 0.63-0.82) had a lower risk of all-cause mortality, whereas those referred for SOB (HR = 1.15, 95% CI: 1.07-1.23) and pre-operative evaluation (HR = 2.11, 95% CI: 1.94-2.30) had an increased risk. In subgroup analysis, referral for palpitations was protective only in those without coronary artery disease (CAD) (HR = 0.75, 95% CI: 0.62-0.90), while SOB increased mortality risk only in those with established CAD (HR = 1.25, 95% CI: 1.10-1.44). CONCLUSIONS: The indication for stress testing is an independent predictor of mortality, showing an interaction with CAD status. Importantly, SOB may be associated with higher mortality risk than chest pain, particularly in patients with CAD