Background Cardiac arrhythmias have not been previously reported in horses while swimming. Objectives To describe the type and frequency of encountered arrhythmias during repetitive swimming cycles. Study design Descriptive observational study. Methods Sixteen horses swam five pool lengths (75 m), each separated by an active recovery walk. Continuous electrocardiograms (ECGs) were recorded (n = 80) and analysed during the pre-swim, swim and active-recovery periods. Arrhythmias were categorised as sinus arrhythmia (SA), sinus block, sinus pause (compensatory and non-compensatory), second degree atrioventricular block (2AVB) for physiological arrhythmias, supraventricular premature depolarisation (SVPD) and ventricular premature depolarisation (VPD) for non-physiological arrhythmias. A linear mixed-effects model was used to examine the effects of repetitive swim lengths on arrhythmias and swimming parameters. Data were reported as median [interquartile range]. Results Fifteen horses (94%) experienced at least one arrhythmia; however, the frequency remained low and 2AVB were only observed during the pre-swim period. The swimming heart rate (HR) was 162 bpm [141;173]. Sinus blocks, sinus pauses, SA, SVPD and VPD were all recorded at least once during swimming. Except for one VPD couplet, all premature depolarisations were isolated. During active-recovery, the HR was 105 bpm [103;106], with SA observed in 13 horses (81%), isolated SVPD in six horses (38%), sinus pause in one horse (6%) but no VPD present. Main limitations Limited number of horses precluding population prevalence assessment. Conclusion and clinical importance High-quality underwater ECGs were acquired in swimming horses for the first time. The frequency of arrhythmias remained low and rare pathological arrhythmias were observed during repetitive swimming and active-recovery cycles. Swimming with active-recovery periods is not a high-risk cardio-arrhythmic exercise.

BACKGROUND:Swimming is used for rehabilitation and conditioning purposes in equine sports medicine. We described the swimming kinematics of the equine forelimbs in Part 1. The aim of Part 2 is to assess stifle, tarsus, and hind fetlock joints kinematics in swimming horses. The objectives were 1- to calculate and compare joint angles during swimming against passive mobilizations (PM), 2- to determine joints angular velocities during a swimming stride cycle.METHODS:Eleven elite endurance horses were used to swim in a 100-meter straight pool. Underwater (swimming) and overground PM videos were recorded from the horses' left side. Joint markers were applied on the lateral hoof wall, lateral metatarsal epicondyle, lateral aspect of the talus, lateral femoral epicondyle, and great trochanter of the femur. As a reference, maximal fetlock, tarsus, and stifle flexion/extension angles were determined during PM overground. Differences between angle extrema, angular velocities, and range of motion (ROM) were statistically compared.RESULTS:The tarsus ROM was similar during PM and swimming. The stifle and fetlock ROM were greater during PM, although the stifle flexion was greater during swimming. The stifle and tarsus had the greatest hindlimb angular velocity during the swimming cycle. Greater angular velocities were observed during the retraction phase for all the hindlimb joints.CONCLUSION:A short retraction phase with great angular velocity for the joints of interest characterized the swimming pattern observed. Swimming may be beneficial in horses when an increased ROM of the tarsus and stifle or a reduced fetlock extension is indicated for rehabilitation purposes.

High-temperature cyclopentadiene pyrolysis was examined behind reflected shock waves in a heated shock tube using several laser absorption diagnostic schemes. A two-color, online-offline sensor near 3335 cm-1 was used to measure time histories of acetylene, while a three-color scheme of diagnostics at 10.532, 10.675, and 11.345 μm yielded measurements of cyclopentadiene and ethylene. Species time histories of cyclopentadiene decomposition and acetylene formation as well as ethylene yields are reported from 1319 to 1678 K at 1.2-1.5 atm. In addition, the overall decomposition rate of cyclopentadiene is reported, and comparisons are made to a number of kinetic models.

Two novel laser absorption diagnostics for allene and propyne are presented. Through examination of the high temperature spectra of the two C3H4 isomers via two fast-wavelength-scanning, broadband external cavity quantum cascade lasers, 1930.38 cm(-1) and 1233.3 cm(-1) were chosen as the wavelengths for a two-species, two-wavelength diagnostic pair that minimizes interference from other species. Absorption cross sections for allene and propyne were measured at each of these wavelengths over 1196-1502 K, at 1.3-1.6 atm. Once characterized, these diagnostics were employed to measure the mutual isomerization rates of allene and propyne over the same temperature range. The two rates are reported as k(A->P) (1202-1502 K) = 2.64 x 10(12)exp(-59,214/RT) +/- 14% and k(P->A) (1196-1494 K) = (4.19 x 10(12))exp(-61,912/RT) +/- 17%. These rates were found to be in excellent agreement with limited past experimental determinations and recently computed rates. Using these rates, the equilibrium constant is also reported as a function of temperature. (C) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Equine performance in endurance racing depends on the interplay between physiological and metabolic processes. However, there is currently no parameter for estimating the readiness of animals for competition. Our objectives were to provide an in-depth characterization of metabolic consequences of endurance racing and to establish a metabolic performance profile for those animals. We monitored metabolite composition, using a broad non-targeted metabolomics approach, in blood plasma samples from 47 Arabian horses participating in endurance races. The samples were collected before and after the competition and a total of 792 metabolites were measured. We found significant alterations between before and after the race in 417 molecules involved in lipids and amino acid metabolism. Further, even before the race starts, we found metabolic differences between animals who completed the race and those who did not. We identified a set of six metabolite predictors (imidazole propionate, pipecolate, ethylmalonate, 2R-3R-dihydroxybutyrate, β-hydroxy-isovalerate and X-25455) of animal performance in endurance competition; the resulting model had an area under a receiver operating characteristic (AUC) of 0.92 (95% CI: 0.85–0.98). This study provides an in-depth characterization of metabolic alterations driven by endurance races in equines. Furthermore, we showed the feasibility of identifying potential metabolic signatures as predictors of animal performance in endurance competition.

Background: Swimming is used for rehabilitation and conditioning purposes in equine sports medicine despite the lack of understanding of equine swimming kinematics. The aim of this study was to assess forelimb joints kinematics (elbow, carpus, and fetlock) in swimming horses. The specific objectives were 1- to calculate and compare joint angles in swimming vs. passive mobilizations (PM), 2- to determine joint angular velocities during a swimming stride cycle. Methods: Eleven elite endurance horses swam in a 100-m straight pool. Underwater (swimming) and overground (PM) videos were recorded from the horses' left side. Joint markers were applied on the lateral hoof wall, lateral metacarpal epicondyle, ulnar carpal bone, lateral humeral epicondyle, and the greater tubercle of humerus, from which elbow, carpus and fetlock angles, and angular velocities were obtained. As a reference, maximal fetlock, carpus, and elbow flexion/extension angles were determined during PM overground. Differences between angle extrema, angular velocities and range of motion (ROM) were compared. Results: Carpus and fetlock ROM were significantly smaller (p < 0.001) during swimming when compared with PM, while there was no difference in elbow ROM between both situations. The carpus had the greatest ROM of all joints during swimming. Absolute angular velocities values of all joints during swimming were greater during retraction than protraction (p < 0.001). When compared to other joints during protraction, the carpus joint reached the highest angular velocity. Conclusion: Swimming, as a rehabilitation exercise, has the potential to benefit horses where great elbow ROM with a moderate carpus and fetlock extension are wanted.

A new strategy for collection of high-temperature broad-band absorption spectra for gas-phase molecules in the mid-infrared Motivation:A lack of knowledge on broad-band molecular absorption at elevated temperatures Novelty:Interplay of a rapid-tuning broad-scan EC-QCL with shock tube facilities (collection rate: >30,000 cm -1 /s) Results and Discoveries: ❑First measurements of ethylene full-band absorption near 10 µm at 1000 K ❑Strong temperature dependence in the Q-branch between 800 -1600 K ❑Readily deployable for molecules that absorb between 3.6 -11.7 µm

Background: Although air pollution is a mixture that includes local and regional emissions sources, local governments currently rely on single-pollutant-based U.S. national ambient air quality standards (NAAQS) to protect health. We developed a framework to assess multi-pollutants' impacts on health outcomes in New York City (NYC) using time-series analyses. Methods: Single- and multi-pollutant Poisson models for ozone, nitrogen dioxide (NO2), and fine particles (PM2.5) were evaluated for multiple outcomes (morbidity models: 2005-2014; mortality models: 2004-2016): (1) asthma-related emergency department visits (ages 6-18); (2) cardiovascular-related hospitalizations (ages 40+); (3) hospitalizations for chronic lung diseases (ages 20+); and (4) cardiovascular (CVD) and all-natural-cause mortality (all ages). Seasonal models were adjusted for within-season trend, temperature, and day-of-week, and considered up to 3-day lagged effects. Attributable fractions (AFs) were estimated considering single and multiple pollutants when associations were found. Results: All outcomes were associated with one or more pollutants at levels below their current NAAQS. Individual pollutants' estimates were sometimes sensitive (e.g., attenuation of risk estimates by 50%) to the addition of another pollutant, and total AFs in multi-pollutant models were typically smaller than the sum of those from single pollutant models. For hospitalization outcomes, AFs from NO2-only models were generally closest to those from corresponding multi-pollutant models (e.g., cold-season NO2-only models for lung diseases and CVD AFs (95% CI): 2.2% (-0.6, 5.0) and 3.3% (1.0, 5.6); NO2 + PM2.5: 2.2% (-1.9, 6.3) and 3.2% (-0.1, 6.5). Mortality outcomes were associated with all three pollutants in the warm season, with ozone-only models most indicative of multi-pollutant effects (e.g. all-cause mortality AFs: ozone only: 1.6% (0.1, 3.7); ozone + PM2.5 + NO2: 1.8% (-1.1, 5.1)).Conclusions: Given the substantial regional source contributions to PM2.5 and ozone, reducing local NO2 emissions (i.e., traffic and buildings) may be most impactful in reducing pollution-associated illness exacerbations in NYC.

We report the first shock tube measurements of formaldehyde (CH 2O) during the first stage ignition of n-heptane, 2-methylhexane and 3,3-dimethylpentane, in highly diluted fuel/oxygen mixtures in the pressure range of 7-10 atm and temperature range of 700-880 K. Combined time histories of all carbonyl (-C = O) species, CO and fuel were also measured simultaneously in an effort to study the impact of fuel structure on the concentration and the rate of evolution of first stage ignition products. Of the three isomers studied in this work, n-heptane was found to be the fastest, while 3,3-dimethylpentane was found to be the slowest. The differences in the time scale of formation, and plateau concentration of the intermediates between the isomers across the entire range of test conditions suggests a strong dependency of the measured time histories to fuel structure. These species therefore act as markers of the Negative Temperature Coefficient (NTC) behavior of fuels and can be used as targets for developing semi-empirical, hybrid chemistry models of complex, multicomponent petroleum derived gasoline and jet fuels. The time histories reported in this work should prove very useful in the refinement of detailed kinetic models of n-heptane, and development of rate rules for branched alkane isomers. (c) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

We present a comprehensive study on the temperature-dependent mid-infrared absorption spectra between 8.4 mu m and 11.7 mu m for a complete list of C-3-C-4 alkenes, namely propene, 1-butene, cis-/trans-2-butene and isobutene, as well as 1,3-butadiene, from room temperature to roughly 10 00 K. The methodology deploys a rapid-tuning, broad-scan external-cavity quantum-cascade laser (EC-QCL) in a shock tube and can provide quantitative absorption information at a rate in excess of 30 cm(-1) /ms at spectral intervals between 0.35-0.6 cm(-1). The experimental procedure was validated with room-temperature, nitrogen-diluted, static spectra measurements for propene, 1-butene, isobutene, and 1,3-butadiene, showing good agreement with existing spectroscopic databases. Spectral measurements were extended to higher temperatures with shock-heated test gas mixtures diluted by argon, at experimental conditions between 60 0-1000 K and 1.5-2.5 atm. The resulting spectra show strong temperature dependence and represent the first experimental collection of broadband high-temperature absorption spectra for these species. The measured high-temperature spectra are in reasonable agreement with predictions from fixed-wavelength absorption cross section correlations in the literature. The data presented are archived in the Stanford ShockGas-IR database and provide useful expansions of the existing knowledge on molecular absorption in the mid-infrared at elevated temperatures. (C) 2020 Elsevier Ltd. All rights reserved.

Routine preprocedural chest and abdomen computed tomography is done prior to trans catheter aortic valve implantation (TAVI), which, in turn, have led to the discovery of radiographic potentially malignant incidental masses (pMIM). It is largely unknown whether pMIM impact the outcomes of patients undergoing TAVI. In this retrospective cohort study from a single center, 1,081 patients underwent TAVI from 2012 to 2016, who had available computed tomographies, survived the index hospitalization, and also had 1 year follow-up data for review. Machine learning (backward propagation neural network)-augmented multivariable regression for mortality by pMIM was conducted. In this cohort of 1,081 patients, the mean age was 79.1 (+/- 9.0), 48.8% were females, 16.8% had a history of prior malignancy, and 21.1% had pMIM. One-year mortality for the entire cohort was 12.6%. The most common prior malignancies were prostate, breast, and lymphoma and the most common pMIM were present in the lung, kidneys, and thyroid. In a fully adjusted regression analysis, neither prior malignancy nor pMIM increased mortality odds. However, having both was associated with a higher 1-year mortality (odds ratio 4.02, 95% confidence interval 1.50 to 10.73, p = 0.006). In conclusion, presence of pMIM alone was not associated with an increased 1-year mortality among patients undergoing TAVI. However, the presence of pMIM and a history of prior malignancy was associated with a significant increase in 1-year mortality. (C) 2020 Elsevier Inc. All rights reserved.

This work presents a novel application of multi-wavelength, multi-species laser absorption methods in the pyrolysis of JP-10 fuel. Two different multi wavelength approaches are used to measure the species from JP-10 pyrolysis in a shock tube at pressures of 2.5–3 atm and temperatures of 1166–1522 K. A five wavelength (5λ) analysis combination produces species time histories for ethylene, cyclopentadiene, and methane formation, as well as estimates of fuel decay. These results are extended further using a seven wavelength (7λ) combination of methods to measure ethylene, cyclopentadiene, propene, methane, allene, 1,3 butadiene, benzene, toluene, and fuel. Supplementary material includes details on the cyclopentadiene cross sections for 10.532 µm, 10.958 µm, and 11.345 µm. Simulations using two recent models are compared to the experimental data and the discrepancies are examined.

Spontaneous nasalization is the emergence of distinctive nasalization in contexts lacking an historical etymological nasal. In Thai, low and mid-low vowels nasalize after /h/ and to a lesser degree after /?/. It has been reasoned that nasalization after /h/ may occur because breathiness and nasalization are acoustically similar; both introduce higher energy at low frequencies and increase spectral tilt. Glottal consonants may generally facilitate nasalization because aerodynamically they do not require velopharyngeal closure. We investigated velopharyngeal opening (VPO) during vowels after /h/ and/?/ and measured spectral tilt (H1-H2). We measured VPO by processing oblique ultra-fast magnetic resonance images of the velopharyngeal port. Four Thai speakers exhibited a complex system of VPO that varied based on vowel height and preceding consonant. Low vowels after /h/ manifested more physiological nasalization than low vowels after /?/, while the former were often produced with higher spectral tilt, which may be indicative of either increased breathiness or nasalization. While VPO is likely responsible for impressions of greater nasalization after /h/, our findings suggest that breathiness and VPO may interact in the spontaneously nasalized vowels of Thai. (C) 2019 Elsevier Ltd. All rights reserved.

Spontaneous nasalization, the emergence of nasalization in contexts lacking an historical nasal phoneme, often occurs during vowels adjacent to glottal constants, as in Thai. One explanation for this nasalization is velopharyngeal underspecification (VPU) of glottal consonants: the lack of any requirement for velar closure. If VPU is the source of spontaneous nasalization in Thai we expect to find greater nasalization during glottal consonants compared to adjacent nasalized vowels. To test this we recorded nasal airflow in six speakers of central Thai. Results showed greater nasal airflow during /h/ compared to following nasalized vowels. This finding suggests that the starting point of nasalization in Thai is the glottal consonant and that nasalization spreads to the following vowel.

A framework for the study of high-temperature hydrocarbon pyrolysis is presented. The proposed framework details a multi-wavelength speciation method using convex optimization, a review of complementary fixed-wavelength laser diagnostics, and a database of high-temperature absorption cross-sections to enable use of the framework for 11 different species. The proposed speciation method involves a vectorized Beer-Lambert system solved under solution constraints using convex optimization. In support of the proposed method, a review of pertinent laser diagnostics and a database of high-temperature absorption cross-sections are also provided. The database includes measured absorption cross-sections of methane (CH4), ethylene (C2H4), propene (C3H6), isobutene (i-C4H8), 1-butene (1-C4H8), benzene (C6H6), toluene (C7H8), and four jet fuels (samples of Jet A, JP5, JP8, and Gevo ATJ) at the wavelengths of 3.1758 mu m, 3.17595 mu m, 3.283 mu m, 3.392 mu m, 3.410 mu m, 10.532 mu m, 10.675 mu m, 10.89 mu m, 10.958 mu m, 10.962 mu m, and 11.345 mu m within the range of 300-1600 K and 0.25-4 atm. The database is comprised of over 1000 high-temperature absorption cross-section measurements from new shock tube experiments, new Fourier transform infrared spectrometer (FTIR) experiments, and an aggregated dataset from the literature. The convex speciation method and cross-section database provided will facilitate laser absorption studies of hydrocarbon pyrolysis used in the development of chemical kinetic mechanisms. (C) 2018 Elsevier Ltd. All rights reserved.

A methodology for the measurement of mid-infrared absorption cross sections of gaseous molecules at high temperatures and pressures is presented. A rapid-tuning, broad-scan external cavity quantum cascade laser with a tuning rate in excess of 30000 cm(-1)s(-1) has been employed in the measurement of full vibrational bands ( > 100 cm(-1)) in shock-heated test gases. The approach is demonstrated with measurements of the absorption cross section of ethylene (C2H4) in the 8.5 mu m to 11.7 mu m region for temperatures from 800 K to 1600 K and pressures from 1 to 5 atm. Decreasing peak strength with temperature is observed as well as pressure-insensitivity. The measurements are compared with existing experimental, empirical, and ab initio databases. Additionally, illustrative absorption cross section measurements of propene (C3H6), 1-butene (1-C4H8), 2-butene (2-C4H8), 1,3-butadiene (1,3-C4H6), and methanol (CH3OH) are presented near 1000 K and 2.3 atm. (C) 2018 Elsevier Ltd. All rights reserved.

Homogeneous and inhomogeneous ignition of real and surrogate fuels were imaged in two Stanford shock tubes, revealing the influence of small particle fragmentation. n-Heptane, iso-octane, and Jet A were studied, each mixed in an oxidizer containing 21% oxygen and ignited at low temperatures (900–1000 K), low pressures (1–2 atm), with an equivalence ratio of 0.5. Visible images (350–1050 nm) were captured through the shock tube endwall using a high-speed camera. Particles were found to arrive near the endwalls of the shock tubes approximately 5 ms after reflection of the incident shock wave. Reflected shock wave experiments using diaphragm materials of Lexan and steel were investigated. Particles collected from the shock tubes after each experiment were found to match the material of the diaphragm burst during the experiment. Following each experiment, the shock tubes were cleaned by scrubbing with cotton cloths soaked with acetone. Particles were observed to fragment after arrival near the endwall, often leading to inhomogeneous ignition of the fuel. Distinctly more particles were observed during experiments using steel diaphragms. In experiments exhibiting inhomogeneous ignition, flames were observed to grow radially until all the fuel within the cross section of the shock tube had been consumed. The influence of diluent gas (argon or helium) was also investigated. The use of He diluent gas was found to suppress the number of particles capable of causing inhomogeneous flames. The use of He thus allowed time history studies of ignition to extend past the test times that would have been limited by inhomogeneous ignition.

BACKGROUND:The Society of Thoracic Surgery (STS) risk score serves as an important determinant of eligibility for transcatheter aortic valve replacement (TAVR). The STS score's validity for predicting TAVR mortality, however, is incompletely understood. This study compares the STS score's discriminatory power for TAVR mortality as compared with surgical aortic valve replacement (SAVR) mortality.METHODS:A retrospective analysis of STS score and 30-day mortality for TAVR patients (n = 426) and SAVR patients (n = 297) at a single institution was performed. The performance of the STS score was evaluated from the standpoint of discriminatory power. The predictive ability of STS for 30-day mortality was detected by generation of receiver operator characteristic (ROC) curves.RESULTS:The STS score possesses predictive ability for 30-day SAVR mortality with an area under the ROC curve of 0.791 (95% confidence interval [CI], 0.690-0.893). The STS score also possesses predictive ability for 30-day TAVR mortality with an area under the ROC curve of 0.674 (95% CI, 0.541-0.807). When stratifying TAVR by access route, the STS score for transfemoral TAVR provides an area under the ROC curve of 0.789 (95% CI, 0.569-1.000). There is not a statistically significant difference in predictive ability between SAVR and TAVR.CONCLUSION:The STS score possesses predictive value for 30-day mortality in both SAVR and TAVR. Although not designed for TAVR, the STS score may provide some insight into TAVR mortality, and therefore serves as an appropriate model for efforts to develop a TAVR-specific risk prediction instrument.