Changes in aorta hemodynamics in Left-Right Type 1 bicuspid aortic valve patients after replacement with bioprosthetic valves: An in-silico study

Bicuspid aortic valve (BAV) is the most common cardiac congenital abnormality with a high rate of concomitant aortic valve and ascending aorta (AAo) pathologic changes throughout the patient's lifetime. The etiology of BAV-related aortopathy was historically believed to be genetic. However, recent studies theorize that adverse hemodynamics secondary to BAVs also contribute to aortopathy, but their precise role, specifically, that of wall shear stress (WSS) magnitude and directionality remains controversial. Moreover, the primary therapeutic option for BAV patients is aortic valve replacement (AVR), but the role of improved post-AVR hemodynamics on aortopathy progression is also not well-understood. To address these issues, this study employs a computational fluid dynamics model to simulate personalized AAo hemodynamics before and after TAVR for a small cohort of 6 Left-Right fused BAV patients. Regional distributions of five hemodynamic metrics, namely, time-averaged wall shear stress (TAWSS) and oscillating shear index (OSI), divergence of wall shear (DWSS), helicity flux integral & endothelial cell activation potential (ECAP), which are hypothesized to be associated with potential aortic injury are computed in the root, proximal and distal ascending aorta. BAVs are characterized by strong, eccentric jets, with peak velocities exceeding 4 m/s and axially circulating flow away from the jets. Such conditions result in focused WSS loading along jet attachment regions on the lumen boundary and weaker, oscillating WSS on other regions. The jet attachment regions also show alternating streaks of positive and negative DWSS, which may increase risk for local tissue stretching. Large WSS magnitudes, strong helical flows and circumferential WSS have been previously implicated in the progression of BAV aortopathy. Post-intervention hemodynamics exhibit weaker, less eccentric jets. Significant reductions are observed in flow helicity, TAWSS and DWSS in localized regions of the proximal AAo. On the other hand, OSI increases post-intervention and ECAP is observed to be low in both pre- and post-intervention scenarios, although significant increases are also observed in this ECAP. These results indicate a significant alleviation of pathological hemodynamics post AVR.

Effect of schooling on flow generated sounds from carangiform swimmers

Computational models are used to examine the effect of schooling on flow generated noise from fish swimming using their caudal fins. We simulate the flow as well as the far-field hydrodynamic sound generated by the time-varying pressure loading on these carangiform swimmers. The effect of the number of swimmers in the school, the relative phase of fin flapping of the swimmers, and their spatial arrangement is examined. The simulations indicate that the phase of the fin flapping is a dominant factor in the total sound radiated into the far-field by a group of swimmers. For small schools, a suitable choice of relative phase between the swimmers can significantly reduce the overall intensity of the sound radiated to the far-field. The relative positioning of the swimmers is also shown to have an impact on the total radiated noise. For a larger school, even highly uncorrelated phases of fin movement between the swimmers in the school are very effective in significantly reducing the overall intensity of sound radiated into the far-field. The implications of these findings for fish ethology as well as the design and operation of bioinspired vehicles are discussed.

Does preoperative opioid use predict outcomes to 6 months following primary unilateral knee or hip arthroplasty for osteoarthritis? A data-linked retrospective study

BACKGROUND

Few Australian studies have examined the incidence of prescribed opioid use prior to primary total knee or total hip arthroplasty (TKA, THA) and whether it predicts post-surgery outcomes. A recent Australian study demonstrated that the prevalence of pre-arthroplasty opioid use was approximately 16%. In the United States, approximately 24% of people undergoing TKA or THA are chronic opioid users preoperatively.

PURPOSE

This study aimed to determine (i) the proportion of TKA and THA patients who use prescribed opioids regularly (daily) before surgery (i.e., opioid use reported between the time of waitlisting and any time up to 3 months before surgery), (ii) if opioid use before surgery predicts (a) complication/readmission rates to 6-months post-surgery, and (b) patient-reported outcomes to 6-months post-surgery.

METHODS

A retrospective cohort study of patients who underwent TKA or THA between January 2013 and June 2018 from two Australian public hospitals was undertaken utilizing linked individual patient-level data from two prospectively collected independent databases comprising approximately 3,500 and 9,500 people (database contained known opioid usage data within the 5-year time frame). Inclusion criteria included (i) primary diagnosis of osteoarthritis of the index joint, (ii) primary elective THA or TKA, and (iii) age ≥ 18 years. Exclusion criteria included (i) revision arthroplasty, (ii) non-elective arthroplasty, (iii) hip hemiarthroplasty, (iv) uni-compartmental knee arthroplasty, and (v) previous unilateral high tibial osteotomy.

RESULTS

Analysis was completed on 1,187 study participants (64% female, 69% TKA, mean (SD) age 67 [9.9]). 30% were using regular opioids preoperatively. Adjusted regression analyses controlling for multiple co-variates indicated no significant association between preoperative opioid use and complications/readmission rates or patient-reported outcomes to 6 months post-surgery. Model diagnostics produced poor discrimination for area under the curves and non-significant goodness of fit tests. Pre-arthroplasty opioid use was associated with lower health-related quality of life (EuroQol-Visual Analogue Scale) compared to non-opioid users undergoing primary THA (mean difference -5.04 [-9.87, -0.22], P = 0.04, Adjusted R2 = 0.06) CONCLUSION: In this study, 30% of patients were using prescribed opioids daily prior to primary TKA or THA. Pre-arthroplasty opioid use was not associated with postoperative adverse events or patient-reported pain, function, or global perceived improvement up to six months post-surgery.

In silico modelling of the effect of pyloric intervention procedures on gastric flow and emptying in a stomach with gastroparesis

Pyloric interventions are surgical procedures employed to increase the gastric emptying rate in gastroparesis patients. In this study, we use an in silico model to investigate the consequences of pyloric intervention on gastric flow and emptying for two phenotypes of gastroparesis: antral hypomotility and decreased gastric tone. The transpyloric pressure gradient predicted by the in silico model, based on viscous fluid flow equations, is compared against in vivo measurements. Both phenotypes exhibit a similar pre-procedural emptying rate reduction, but after pyloric surgery, antral hypomotility case with preserved gastric tone shows significant improvements in emptying rates, up to 131%, accompanied by bile reflux from the duodenum into the stomach. Conversely, severely reduced gastric tone cases exhibited a post-procedural reduction in the net emptying rate due to the relatively larger bile reflux. In cases with a combination of antral hypomotility and reduced gastric tone, post-procedural improvements were observed only when both conditions were mild. Our findings highlight the pivotal role of the relative increase in pyloric orifice diameter in determining post-operative emptying rates. The study suggests a possible explanation for the selective response of patients toward these procedures and underscores the potential of in silico modelling to generate valuable insights to inform gastric surgery.

A pilot study of intraoperative application of cooled radiofrequency to reduce post-operative pain following total knee arthroplasty

BACKGROUND

Total Knee Arthroplasty (TKA) is a successful treatment for end stage knee osteoarthritis (OA), but can be associated with significant pain in the early post-operative period. Cooled radiofrequency ablation (CRFA) has reported to reduce knee OA pain by targeting the periarticular nerves. The objective of this pilot study was to assess the effectiveness of intra-operative CRFA for reducing pain and opiate use after TKA.

METHODS

This was a non randomised prospective study with control group. Participants were sequentially recruited preoperatively and underwent TKA, with CRFA to 6 targeted sites prior to cementing of implants, and were compared to controls who underwent TKA without CRFA. The primary outcome was Day 3 pain scores, and secondary outcomes included week one pain scores, and opiate use up to six weeks post-operative.

RESULTS

17 participants were recruited to the control group and 12 were recruited to the CRFA group. There was no significant difference in demographics or baseline pain scores between the groups. On day 2 the CRFA group had a lower mean pain VAS score of 3.2 compared to 4.4 in the control group (p = 0.03). The mean post operative VAS pain score did not differ between the groups for Day 1, 3, 4, or any other time points up to 6 weeks. There were no significant reduction in opiate use in the CRFA group compared to the control group. There were no adverse events.

CONCLUSION

This study demonstrated intra-operative CRFA was not effective in reducing pain by 50% after TKA in a pilot study.

Pancreatic duct pressure: A review of technical aspects and clinical significance

Pancreatic duct pressure (PDP) dynamics comprise an intricately modulated system that helps maintain homeostasis of pancreatic function. It is affected by various factors, including the rate of pancreatic fluid secretion, patency of the ductal system, sphincter of Oddi function, and pancreatic fluid characteristics. Disease states such as acute and chronic pancreatitis can alter the normal PDP dynamics. Ductal hypertension or increased PDP is suspected to be involved in the pathogenesis of pancreatic pain, endocrine and exocrine pancreatic insufficiency, and recurrent pancreatitis. This review provides a comprehensive appraisal of the available literature on PDP, including the methods used in the measurement and clinical implications of elevated PDP.

Efficient trapping and destruction of SARS-CoV-2 using PECO-assisted Molekule air purifiers in the laboratory and real-world settings

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted human-to-human via aerosols and air-borne droplets. Therefore, capturing and destroying viruses from indoor premises are essential to reduce the probability of human exposure and virus transmission. While the heating, ventilation, and air conditioning (HVAC) systems help in reducing the indoor viral load, a targeted approach is required to effectively remove SARS-CoV-2 from indoor air to address human exposure concerns. The present study demonstrates efficient trapping and destruction of SARS-CoV-2 via nano-enabled filter technology using the UV-A-stimulated photoelectrochemical oxidation (PECO) process. Aerosols containing SARS-CoV-2 were generated by nebulization inside an air-controlled test chamber where an air purifier (Air Mini+) was placed. The study demonstrated the efficient removal of SARS-CoV-2 (99.98 %) from the test chamber in less than two minutes and PECO-assisted destruction (over 99%) on the filtration media in 1 h. Furthermore, in a real-world scenario, the Molekule Air-Pro air purifier removed SARS-CoV-2 (a negative RT-qPCR result post-running the filter device) from the circulating air in a COVID-19 testing facility. Overall, the ability of two FDA-approved class II medical devices, Molekule Air-Mini+ and Air-Pro air purifiers, to remove and destroy SARS-CoV-2 in indoor settings was successfully demonstrated. The study indicates that as the "tripledemic" of COVID-19, influenza, and respiratory syncytial virus (RSV) overwhelm the healthcare facilities in the USA, the use of a portable air filtration device will help contain the spread of the viruses in close door facilities, such as in schools and daycare facilities.

Rate of Infection and Causative Organisms in a Lateral Approach Total Ankle Replacement

BACKGROUND

Although the rate of both superficial and deep infection in total ankle replacement (TAR) can reach up to 13% as reported in the literature, there is little information on the causative organisms, especially in laterally implanted prosthesis. This study aims to identify organisms causing infections to ultimately guide to better antibiotic prophylaxis.

METHODS

Between September 2016 and April 2021, we retrospectively reviewed patients who had an infection after a lateral TAR. Cause of the infection, causative organisms, and implant survival were recorded.

RESULTS

Out of 130 patients, 10 of 130 patients (7.6%) had a superficial infection whereas 3 of 130 patients (2.3%) had a deep infection. Staphylococcus and Pseudomonas species were found to be the most common. No significant difference was found between the type of plate used for fibula fixation regarding wound dehiscence.

CONCLUSIONS

Infection after lateral TAR is generally polymicrobial in nature with Staphylococcus and Pseudomonas species being the most common.

LEVEL OF EVIDENCE

Level IV Case Series.

Does Radiographic Alignment Correlate With Patient-Reported Functional Outcomes and Posttreatment Complications in Older Patients Treated for Wrist Fractures?

PURPOSE

Surgical treatment of distal radius fractures provides better fracture alignment than closed reduction; however, surgical treatment does not lead to better patient-reported function at 12 months. The aims of this study were to report the radiographic outcomes from the Combined Randomized and Observational Study of Surgery for Fractures In the distal Radius in the Elderly trial, investigate the association between radiographic outcomes and patient-reported function, and explore whether this association was affected by posttreatment complications and direction of malalignment.

METHODS

This study used the outcomes of the Combined Randomized and Observational Study of Surgery for Fractures In the distal Radius in the Elderly trial, which is a combined randomized and observational trial that compared volar-locking plate fixation with closed reduction and cast immobilization, to treat distal radius fractures in patients aged ≥60 years. Four radiographic outcomes (dorsal angulation, radial inclination, ulnar variance, and articular step) were reported at the following three time frames: (1) baseline, (2) after treatment, and (3) ≥6 weeks by treatment group. Secondary analysis was correlation of 12-month patient-reported function scores with 6-week radiographic measures for each of four radiographic parameters, and a subgroup analysis was conducted to investigate if this was affected by posttreatment complications. Tertiary analysis investigated if direction of malalignment affected the secondary analysis.

RESULTS

We recruited 300 participants (166 randomized and 134 observational); 113 had volar-locking plate fixation, and 187 had closed reduction. There were no between-group differences for each of the four pretreatment radiographic parameters, but there were between-treatment group differences for all four radiographic parameters apart from articular step. We found no association between patient-reported function at 12 months and each of the four radiographic parameters at 6 weeks. This lack of association was unaffected by posttreatment complications and the direction of malalignment.

CONCLUSIONS

For patients with wrist fractures aged ≥60 years, final radiographic alignment did not correlate with patient-reported function at 12 months. These findings were not affected by treatment type, and there was no association between radiographic alignment and posttreatment complications.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Preliminary insights into patient preparedness for knee or hip arthroplasty: a descriptive survey study

OBJECTIVE

Knowledge-based preparedness for surgery is achieved through education. It is unclear which of brief or extended education programs prior to knee or hip arthroplasty provides better patient preparedness. Using the Patient Preparedness for Surgery survey, we investigated whether people awaiting arthroplasty attending a hospital that provided education over multiple visits via a pre-surgery management program ('Extended') report superior preparedness compared to those attending a hospital in the same health district that only provides education at the pre-admission clinic assessment ('Brief').

RESULTS

A consecutive sample of 128 people (n = 101, 'Extended', n = 27 'Brief') completed the anonymized survey. COVID-19 related service disruptions undermined the sample size, reducing statistical power. The pre-specified superiority of the Extended program (a relative 20% more reporting 'agree'/'strongly agree') was not observed for 'Overall preparedness' [95% (Extended) vs. 89% (Brief), p = 0.36]. Between-group differences exceeding 20% relative superiority were observed for three preparedness sub-domains ['Alternatives explained' (52 vs. 33%, p = 0.09); 'Prepared for home' (85 vs. 57%, p < 0.01); 'Recall of complications' (42 vs 26%, p = 0.14)]. The preliminary findings suggest an extended education program potentially yields better patient-reported preparedness in some preparedness sub-domains, but not all.

Reconstructing the pressure field around swimming fish using a physics-informed neural network

Fish detect predators, flow conditions, environments, and each other through pressure signals. Lateral line ablation is often performed to understand the role of pressure sensing. In this study, the authors propose a non-invasive method for reconstructing the instantaneous pressure field sensed by a fish's lateral line system from 2D particle image velocimetry (PIV) measurements. The method uses a physics-informed neural network (PINN) to predict an optimized solution for the pressure field near and on the fish's body that satisfy both the Navier-Stokes equations and the constraints put forward by the PIV measurements. The method was validated using a direct numerical simulation of a swimming mackerel, Scomber scombrus, and was applied to experimental data of a turning zebrafish, Danio rerio. The results demonstrate that this method is relatively insensitive to the spatio-temporal resolution of the PIV measurements and accurately reconstructs the pressure on the fish's body.

Trends in management of adult tarsometatarsal joint injuries in a contemporary Australian context: a nationwide study of claims data over 20 years

BACKGROUND

Traumatic tarsometatarsal joint (TMTJ) injuries are uncommon, but can cause significant morbidity due to delayed or missed diagnosis. Recent evidence highlights the importance of achieving anatomical reduction via operative management. This study aims to analyse trends in rates of open reduction internal fixation (ORIF) for Lisfranc injuries in Australia according to Nationwide claims data.

METHODS

Claims according to the Medicare Benefits Schedule (MBS) on ORIF of traumatic TMTJ injuries were collated for the period from January 2000 to December 2020. Paediatric patients were excluded. Two negative binomial models were utilized to analyse the trends in TMTJ injuries over time after controlling for sex, age group and population changes. Results were absolute and per 100 000 population.

RESULTS

7840 patients underwent TMTJ ORIF over the period studied. There was a mean yearly increase of 12% (P < 0.001). Age group (P < 0.001) and year (P < 0.001) were significant predictors for TMTJ fixation, whilst sex was not (P = 0.48). Patients older than 65 years were noted to have a 53% lower rate of TMTJ ORIF per person, when compared to the reference group of 25-34 year-olds (P < 0.001). Five-year block analysis revealed increases in rate of fixation for all age groups.

CONCLUSION

Rates of operative fixation for TMTJ injuries are increasing in Australia. This is likely due to improved diagnostics, understanding of optimal treatment goals, and increased orthopaedic subspecialisation. Further studies with clinical and patient reported outcomes, as well as comparing rates of operative intervention to incidence, will be useful.

A Shoulder/Elbow Triage and Assessment model of care reduced a public orthopaedic shoulder/elbow clinic waitlist with high patient satisfaction

BACKGROUND

Patients referred to public orthopaedic clinics can experience long waiting times before assessment. This study aims to evaluate the effectiveness of a collaborative Shoulder/Elbow Triage and Assessment (SHELTA) model of care involving orthopaedic surgeons and physiotherapists to reduce the waitlist and improve service and clinical outcomes for patients on an orthopaedic shoulder/elbow clinic waitlist.

METHODS

Patients on the waitlist were triaged by surgeons and physiotherapists and invited to an assessment by experienced physiotherapists. Patients were treated nonoperatively or transferred to orthopaedic management based on clinical discussion. The primary outcome was the number of patients on the waitlist. Secondary outcomes included adverse events, patient satisfaction, re-referral and conversion to surgery rates. Pain, function and patient global impression of change were recorded for participants managed nonoperatively.

RESULTS

From July 2019 to December 2019, the waitlist reduced from 451 to 298 patients with no adverse events. Seventy-nine patients could not be contacted and 25 no longer required assessment, and were removed from the waitlist. Nonoperatively managed participants reported satisfaction with the service, a median score of 6 on a 7-point Patient Global Impression of Change scale, change in pain of -2.5/10 (95% CI -3.3, -1.7; P < 0.001) on a numerical pain rating scale, and change in function of -17.4/100 (95% CI: -24.1, -10.8; P < 0.001) on the QuickDASH, indicating improvement.

CONCLUSIONS

The SHELTA model of care effectively reduced the number of patients on an orthopaedic shoulder/elbow clinic waitlist with good service and clinical outcomes.

Towards Longitudinal Monitoring of Leaflet Mobility in Prosthetic Aortic Valves via In-Situ Pressure Sensors: In-Silico Modeling and Analysis

BACKGROUND

Transcatheter aortic valves (TAVs) are susceptible to leaflet thrombosis which may lead to thromboembolic events, and early detection and intervention are believed to be the key to avoiding such adverse outcomes. An embedded sensor system installed on the valve stent, coupled with an appropriate machine learning-based continuous monitoring algorithm can facilitate early detection to predict severity of reduced leaflet motion (RLM) and avoid adverse outcomes.

METHODS

We present a data-driven, in silico, proof-of-concept analysis of a pressure microsensor based system for quantifying RLM in TAVs. We generate a dataset of 21 high-fidelity transvalvular flow simulations with healthy and mildly stenotic TAVs to train a logistic regression model to correlate individual leaflet mobility in each simulation with principal components of corresponding hemodynamic pressure recorded at strategic locations of the TAV stent. A separate test dataset of 7 simulations is also generated for prospective assessment of model performance.

RESULTS

An array of 6 sensors embedded on the TAV stent, with two sensors tracking individual leaflet, successfully correlates leaflet mobility with recorded pressure. The sensors are placed along leaflet centerlines, one in the sinus, and the other at the sino-tubular junction. The regression model is tuned using cross-validation to achieve high accuracy on both training (R² = 0.93) and test (R² = 0.77) sets.

CONCLUSION

Discrete blood pressure recordings on TAV stents can be successfully correlated with individual leaflet mobility. Further development of this technology can enable longitudinal monitoring of TAVs and early detection of valve failure.

Early Clinical Outcomes and Complications of Transfibular Total Ankle Arthroplasty: The Australian Experience

BACKGROUND

We report the short-term outcomes of a retrospective cohort of Trabecular Metal total ankle arthroplasties (TAAs) via a transfibular approach from a single, nondesigner surgeon in Australia.

METHODS

This was a retrospective cohort study. Demographic, clinical, and patient-reported outcome measures (PROMs) were collected. The primary outcome was the Foot and Ankle Outcome Score (FAOS), and secondary outcomes included patient satisfaction, the EuroQol-5 Dimension (EQ5D), and complications including revision rates.

RESULTS

Between 2016 and 2019, 84 trabecular metal prostheses were implanted in 84 patients. Mean age (SD) at time of surgery was 68 (7.8) years, and 46 (55%) were male. Mean follow-up (SD) was 26.1 (13) months. There were significant (P < .001) improvements in the FAOS in the subscales of pain (47.9 to 79.1), activities of daily living (59.5 to 83.7), and quality of life (25.5 to 60.2) and EQ-5D (0.55 to 0.75) (P < .001), and overall satisfaction was 69.6%. The commonest complications were wound infection or breakdown (11.9%, n=10), fibular nonunion (3.5%), plate irritation (3.5%), and tibial nerve neuropathy (3.5%). There were no thromboembolic complications. Implant survivorship was 100%, with Trabecular Metal components retained in all patients. Two patients developed deep infection, with 1 requiring debridement and polyethylene exchange. No patients experienced implant loosening.

CONCLUSION

Our results demonstrate that the trabecular metal survival rates are comparable with other total ankle implants in the Australian Orthopaedic Association National Joint Replacement Registry and as published in other international literature. Overall patient satisfaction was high, as were PROMs. However, the data highlight potential complications uniquely associated with this implant. The authors believe that these figures support TAA via a transfibular approach as a viable option in the treatment of ankle arthritis.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

Minimum 5-Year Follow-up Results: CROSSBAT (Combined Randomised and Observational Study of Surgery vs No Surgery for Type B Ankle Fracture Treatment)

BACKGROUND

Isolated Weber B, AO (Association for the Study of Internal Fixation) type 44B ankle fractures with no fracture to the medial side are the most common type of ankle fracture and may be treated with internal fixation or without surgery.This study aimed to determine if surgery is superior to nonsurgical management for the treatment of these fractures after a minimum 5-year follow-up.

METHODS

Design: A pragmatic, multicenter, single-masked, randomized controlled trial with minimum 5-year follow-up. Setting/participants/interventions: Participants between 18 and 65 years with AO type 44B ankle fracture and minimal talar shift were recruited from 22 hospitals in Australia and New Zealand. Participants willing to be randomized were randomly allocated to undergo surgical fixation followed by mobilization in a walking boot for 6 weeks. Those treated nonsurgically were managed in a walking boot for 6 weeks. Outcome assessors were masked for the treatment allocation. Primary outcomes: Patient-reported ankle function using the American Academy of Orthopaedic Surgeons Foot and Ankle Outcomes Questionnaire (FAOQ) and the physical component summary (PCS) of the SF-12v2 General Health Survey at 12 months postinjury and at minimum 5 years post injury. Primary analysis was intention-to-treat.

RESULTS

Of the 160 (80 surgical, 80 nonoperative) randomized patients included in the CROSSBAT analysis, 77 (40 surgical, 37 nonoperative) were followed up for repeat analysis at minimum 5-year follow-up (mean 7.3 years, range 5.1-8.9). This cohort demonstrated that surgery was not associated with clinically or statistically significant differences compared to nonoperative management for the FAOQ (51.7 vs 49.6; mean difference 2.1, 95% CI -2.1 to 6.2, P = .95), or the PCS (51.5 vs 49.1; mean difference 2.3, 95% CI -2.0 to 6.7, P = .54). The surgical cohort had a higher rate of any adverse events (odds ratio 3.7, 95% CI 1.2-11.6, P = .04).

CONCLUSION

The results of this study suggest that surgical management is not superior to nonsurgical management in type B ankle (fibula) fractures with minimal talar shift over a 5-year period and is associated with increased adverse events.

LEVEL OF EVIDENCE

Level II, randomized clinical trial.

Improved swimming performance in schooling fish via leading-edge vortex enhancement

The hydrodynamics of schooling fish has been the subject of continued investigation over the last 50 years; fish schools exhibit a variety of arrangements and several distinct mechanisms have been proposed to explain the hydrodynamic benefits of schooling. In the current study, we use direct numerical simulations to show that a caudal fin swimmer trailing another similar swimmer can significantly improve its swimming performance by positioning itself such that the wake-induced flow of the leading fish, enhances the leading-edge vortex (LEV) on the fin of the trailing fish. Improvements of up to 12% in both the thrust and efficiency of the trailing fish are possible with this mechanism. The mechanisms underlying these interactional effects are quantitatively analyzed by applying the force partitioning method, a powerful data-driven method that partitions the pressure forces on the fish into mechanistically distinct components. The analysis reveals that the LEV on the fin dominates the overall thrust production for these swimmers and its enhancement therefore provides an effective and robust means for harnessing fish-fish hydrodynamic interactions in a school. In addition to confirming the potential energetic benefits of schooling, the LEV enhancement mechanism could be exploited in coordinated swimming of bioinspired multi-vehicle or multi-foil flapping foil propulsion systems.

Effect of stomach motility on food hydrolysis and gastric emptying: Insight from computational models

The peristaltic motion of stomach walls combines with the secretion of digestive enzymes to initiate the process that breaks down food. In this study, the mixing, breakdown, and emptying of a liquid meal containing protein is simulated in a model of a human stomach. In this model, pepsin, the gastric enzyme responsible for protein hydrolysis, is secreted from the proximal region of the stomach walls and allowed to react with the contents of the stomach. The velocities of the retropulsive jet induced by the peristaltic motion, the emptying rate, and the extent of hydrolysis are quantified for a control case as well as for three other cases with reduced motility of the stomach, which may result from conditions such as diabetes mellitus. This study quantifies the effect of stomach motility on the rate of food breakdown and its emptying into the duodenum and we correlate these observations with the mixing in the stomach induced by the wall motion.

Performance evaluation of activated carbon sorbents for indoor air purification during normal and wildfire events

Volatile organic compounds (VOCs) are a significant class of indoor air pollutants and are known for their adverse effects on health. A common strategy to reduce indoor VOC levels is to use sorbents, including activated carbons (ACs). The amount of activated carbon is critical to achieving a reasonable AC filter lifetime in an air purification device. The study aims to estimate the amount of carbon needed in a typical indoor environment and in a heavy use setting such as during cooking, agriculture field fires, or wildfires. The problem is complex as various types of ACs are used, and the type and concentration of VOCs in the indoor environment also vary in different settings. Therefore, literature data on thermophysical parameters for 45 AC-VOC pairs was used to estimate the required amount of AC under a given set of conditions. The study uses modeling distributions of the footprint of suitable carbon filters for the removal of common VOCs encountered indoors for a period of 30 days. It was found that while 50% of AC-VOC pairs surveyed will require about 190-370 g at low indoor VOCs levels of 0.1-1 μmol/m³(considered a good clean indoor environment), up to 1.1 kg of ACs are needed for a carbon filter to survive 30 days in a typical indoor environment (VOCs levels of 10 μmol/m³). On the other hand, 3-15 kg or more AC will be needed in a filter to survive 30 days during adverse events such as wildfires. The objective of the present study is to aid consumers and businesses in making an informed decision on the type of AC-based indoor air filters that meet their needs. Using this data, an open-access online calculator is being developed to predict the amount of carbon needed in a filter/device at any specific indoor air condition.

Quantifying the Effect of Body Habitus On Cardiac Auscultation via Computational Hemoacoustics

The effect of body habitus on auscultation of heart murmurs is investigated via computational hemoacoustic modeling. The source of the heart murmur is first obtained from a hemodynamic simulation of blood flow through a stenosed aortic valve. This sound source is then placed at the aortic valve location in four distinct human thorax models and the propagation of the murmur in each thorax model simulated by solving the elastic wave equations in the time-domain. Placing the same sound source in different thorax models allows for the disambiguation of the effect of body habitus on cardiac auscultation. The surface acceleration resulting from the murmur on each subject's chest surface shows that subjects with higher body-mass index and thoracic cross-sectional area yield smaller acceleration values for the S1 sound. Moreover, the spectral analysis of the signal shows that slope from linear regression in the normal heart sound frequency range (10 - 150 Hz) is larger for children at the aortic, pulmonic, and mitral auscultation points compared to that for adults. The slope in the murmur frequency range (150-400 Hz) was larger for female subjects at the mitral point compared to that for male subjects. The trends from the results show the potential of the proposed computational method to provide quantitative insights regarding the effect of various anatomical factors on cardiac auscultation.

A Noninvasive Assessment of Flow Based on Contrast Dispersion in Computed Tomography Angiography: A Computational and Experimental Phantom Study

Transluminal attenuation gradient (TAG), defined as the gradient of the contrast agent attenuation drop along the vessel, is an imaging biomarker that indicates stenosis in the coronary arteries. The transluminal attenuation flow encoding (TAFE) equation is a theoretical platform that quantifies blood flow in each coronary artery based on computed tomography angiography (CTA) imaging. This formulation couples TAG (i.e., contrast dispersion along the vessel) with fluid dynamics. However, this theoretical concept has never been validated experimentally. The aim of this proof-of-principle phantom study is to validate TAFE based on CTA imaging. Dynamic CTA images were acquired every 0.5 s. The average TAFE estimated flow rates were compared against four predefined pump values in a straight (20, 25, 30, 35, and 40 ml/min) and a tapered phantom (25, 35, 45, and 55 ml/min). Using the TAFE formulation with no correction, the flow rates were underestimated by 33% and 81% in the straight and tapered phantoms, respectively. The TAFE formulation was corrected for imaging artifacts focusing on partial volume averaging and radial variation of contrast enhancement. After corrections, the flow rates estimated in the straight and tapered phantoms had an excellent Pearson correlation of r = 0.99 and 0.87 (p < 0.001), respectively, with only a 0.6%±0.2 mL/min difference in estimation of the flow rate. In this proof-of-concept phantom study, we corrected the TAFE formulation and showed a good agreement with the actual pump values. Future clinical validations are needed for feasibility of TAFE in clinical use.

Computational modeling of drug dissolution in the human stomach: Effects of posture and gastroparesis on drug bioavailability

The oral route is the most common choice for drug administration because of several advantages, such as convenience, low cost, and high patient compliance, and the demand and investment in research and development for oral drugs continue to grow. The rate of dissolution and gastric emptying of the dissolved active pharmaceutical ingredient (API) into the duodenum is modulated by gastric motility, physical properties of the pill, and the contents of the stomach, but current in vitro procedures for assessing dissolution of oral drugs are limited in their ability to recapitulate this process. This is particularly relevant for disease conditions, such as gastroparesis, that alter the anatomy and/or physiology of the stomach. In silico models of gastric biomechanics offer the potential for overcoming these limitations of existing methods. In the current study, we employ a biomimetic in silico simulator based on the realistic anatomy and morphology of the stomach (referred to as "StomachSim") to investigate and quantify the effect of body posture and stomach motility on drug bioavailability. The simulations show that changes in posture can potentially have a significant (up to 83%) effect on the emptying rate of the API into the duodenum. Similarly, a reduction in antral contractility associated with gastroparesis can also be found to significantly reduce the dissolution of the pill as well as emptying of the API into the duodenum. The simulations show that for an equivalent motility index, the reduction in gastric emptying due to neuropathic gastroparesis is larger by a factor of about five compared to myopathic gastroparesis.

Plating vs Closed Reduction for Fractures in the Distal Radius in Older Patients: A Secondary Analysis of a Randomized Clinical Trial

Importance

Distal radius fractures are common and are managed with or without surgery. Current evidence indicates surgical treatment is not superior to nonsurgical treatment at 12 months.

Objective

Does surgical treatment for displaced distal radius fractures in patients 60 years or older provide better patient-reported wrist pain and function outcomes than nonsurgical treatment at 24 months?

Design, Setting, and Participants

In this secondary analysis of a combined multicenter randomized clinical trial (RCT) and a parallel observational study, 300 patients were screened from 19 centers in Australia and New Zealand. Of these, 166 participants were randomized to surgical or nonsurgical treatment. Participants who declined randomization (n = 134) were included in the parallel observational group with the same treatment options and follow-up. Participants were followed up at 3, 12, and 24 months by a blinded assessor. The 24-month outcomes are reported herein. Data were collected from December 1, 2016, to December 31, 2020, and analyzed from February 4 to October 21, 2021.

Interventions

Surgical treatment consisting of open reduction and internal fixation using a volar-locking plate (VLP group) and nonsurgical treatment consisting of closed reduction and cast immobilization (CR group).

Main Outcomes and Measures

The primary outcome was patient-reported function using the Patient-Rated Wrist Evaluation (PRWE) questionnaire. Secondary outcomes included health-related quality of life, wrist pain, patient-reported treatment success, patient-rated bother with appearance, and posttreatment complications.

Results

Among the 166 randomized and 134 observational participants (300 participants; mean [SD] age, 71.2 [7.5] years; 269 women [89.7%]), 151 (91.0%) randomized and 118 (88.1%) observational participants were followed up at 24 months. In the RCT, no clinically important difference occurred in mean PRWE scores at 24 months (13.6 [95% CI, 9.1-18.1] points for VLP fixation vs 15.8 [95% CI, 11.3-20.2] points for CR; mean difference, 2.1 [95% CI, -4.2 to 8.5]; P = .50). There were no between-group differences in all other outcomes except for patient-reported treatment success, which favored VLP fixation (33 of 74 [44.6%] in the CR group vs 54 of 72 [75.0%] in the VLP fixation group reported very successful treatment; P = .002). Rates of posttreatment complications were generally low and similar between treatment groups, including deep infection (1 of 76 [1.3%] in the CR group vs 0 of 75 in the VLP fixation group) and complex regional pain syndrome (2 of 76 [2.6%] in the CR group vs 1 of 75 [1.3%] in the VLP fixation group). The 24-month trial outcomes were consistent with 12-month outcomes and with outcomes from the observational group.

Conclusions and Relevance

Consistent with previous reports, these findings suggest that VLP fixation may not be superior to CR for displaced distal radius fractures for patient-rated wrist function in persons 60 years or older during a 2-year period. Significantly higher patient-reported treatment success at 2 years in the VLP group may be attributable to other treatment outcomes not captured in this study.

Trial Registration

ANZCTR.org Identifier: ACTRN12616000969460.

Computational Modeling of Aortic Stenosis With a Reduced Degree-of-Freedom Fluid-Structure Interaction Valve Model

In this study, a novel reduced degree-of-freedom (rDOF) aortic valve model is employed to investigate the fluid-structure interaction (FSI) and hemodynamics associated with aortic stenosis. The dynamics of the valve leaflets are determined by an ordinary differential equation with two parameters and this rDOF model is shown to reproduce key features of more complex valve models. The hemodynamics associated with aortic stenosis is studied for three cases: a healthy case and two stenosed cases. The focus of the study is to correlate the hemodynamic features with the source generation mechanism of systolic murmurs associated with aortic stenosis. In the healthy case, extremely weak flow fluctuations are observed. However, in the stenosed cases, simulations show significant turbulent fluctuations in the ascending aorta, which are responsible for the generation of strong wall pressure fluctuations after the aortic root mostly during the deceleration phase of the systole. The intensity of the murmur generation increases with the severity of the stenosis, and the source locations for the two diseased cases studied here lie around 1.0 inlet duct diameters (Do) downstream of the ascending aorta.

Computational Modeling of Drug Dissolution in the Human Stomach

A computational model of drug dissolution in the human stomach is developed to investigate the interaction between gastric flow and orally administrated drug in the form of a solid tablet. The stomach model is derived from the anatomical imaging data and the motion and dissolution of the drug in the stomach are modeled via fluid-structure interaction combined with mass transport simulations. The effects of gastric motility and the associated fluid dynamics on the dissolution characteristics are investigated. Two different pill densities are considered to study the effects of the gastric flow as well as the gravitational force on the motion of the pill. The average mass transfer coefficient and the spatial distributions of the dissolved drug concentration are analyzed in detail. The results show that the retropulsive jet and recirculating flow in the antrum generated by the antral contraction wave play an important role in the motion of the pill as well as the transport and mixing of the dissolved drug concentration. It is also found that the gastric flow can increase the dissolution mass flux, especially when there is substantial relative motion between the gastric flow and the pill.

Post-cricoid and Upper Oesophagus Cancers Treated with Organ Preservation Using Intensity-modulated Image-guided Radiotherapy: a Phase II Prospective Study of Outcomes, Toxicity and Quality of Life

AIMS

To prospectively examine the outcomes, toxicity and quality of life (QoL) of patients with post-cricoid and upper oesophagus (PCUE) cancers treated with an organ-preservation approach of (chemo)-radiotherapy using intensity-modulated image-guided radiotherapy (IM-IGRT).

MATERIALS AND METHODS

This phase II prospective study was conducted at a tertiary cancer centre from February 2017 to January 2020. Forty patients with squamous cell carcinoma of PCUE of stage T1-3, N0-2, M0 were accrued. Gross exolaryngeal extension/dysfunctional larynx were major exclusion criteria. Patients received 63-66 Gy in once-daily fractions using volumetric modulated arc therapy with daily IGRT. Outcome measures included disease-related outcomes, patterns of failure, Radiation Therapy Oncology Group toxicities, feeding tube dependency and QoL.

RESULTS

The median follow-up was 22 months. Twenty-six (87.5%) patients had locoregionally advanced disease and 34 (85%) patients received (chemo)-radiotherapy. A complete response was observed in 26 (65%) patients. The 2-year locoregional control, event-free survival and cause-specific survival were 59.6%, 40.2% and 44.8%, respectively. The volume of primary tumour (GTVPvol) exceeding 28 cm³ had inferior overall survival (P = 0.005) on univariate analysis. Multivariable analysis showed GTVPvol and positron emission tomography-computed tomography maximum standardised uptake value to be independently predictive for event-free and overall survival. A feeding tube requirement at presentation was seen in 11 (27.5%) patients, whereas long-term feeding tube dependency at 6 months was seen in 10 (37%) patients. For QoL, a statistical improvement in pain, appetite loss and swallowing was observed over time.

CONCLUSION

Although the outcomes of PCUE cancers remain dismal, the use of state of the art diagnostic modalities, careful case selection and modern radiotherapy techniques improved outcomes as compared with before in this exclusive analysis of PCUE cancers.

Detecting Aortic Valve Anomaly From Induced Murmurs: Insights From Computational Hemodynamic Models

Patients who receive transcatheter aortic valve replacement are at risk for leaflet thrombosis-related complications, and can benefit from continuous, longitudinal monitoring of the prosthesis. Conventional angiography modalities are expensive, hospital-centric and either invasive or employ potentially nephrotoxic contrast agents, which preclude their routine use. Heart sounds have been long recognized to contain valuable information about individual valve function, but the skill of auscultation is in decline due to its heavy reliance on the physician's proficiency leading to poor diagnostic repeatability. This subjectivity in diagnosis can be alleviated using machine learning techniques for anomaly detection. We present a computational and data-driven proof-of-concept analysis of a novel, auscultation-based technique for monitoring aortic valve, which is practical, non-invasive, and non-toxic. However, the underlying mechanisms leading to physiological and pathological heart sounds are not well-understood, which hinders development of such a technique. We first address this by performing direct numerical simulations of the complex interactions between turbulent blood flow in a canonical ascending aorta model and dynamic valve motion in 29 cases with healthy and stenotic valves. Using the turbulent pressure fluctuations on the aorta lumen boundary, we model the propagation of heart sounds, as elastic waves, through the patient's thorax. The heart sound may be recorded on the epidermal surface using a stethoscope/phonocardiograph. This approach allows us to correlate instantaneous hemodynamic phenomena and valve motion with the acoustic response. From this dataset we extract "acoustic signatures" of healthy and stenotic valves based on principal components of the recorded sound. These signatures are used to train a linear discriminant classifier by maximizing correlation between recorded heart sounds and valve status. We demonstrate that this classifier is capable of accurate prospective detection of anomalous valve function and that the principal component-based signatures capture prominent audible features of heart sounds, which have been historically used by physicians for diagnosis. Further development of such technology can enable inexpensive, safe and patient-centric at-home monitoring, and can extend beyond transcatheter valves to surgical as well as native valves.

Prosthetic Valve Monitoring via In Situ Pressure Sensors: In Silico Concept Evaluation using Supervised Learning

PURPOSE

Patients receiving transcatheter aortic valve replacement (TAVR) can benefit from continuous, longitudinal monitoring of valve prosthesis to prevent leaflet thrombosis-related complications. We present a computational proof-of-concept study of a novel, non-invasive and non-toxic valve monitoring technique for TAVs which uses pressure measurements from microsensors embedded on the valve stent. We perform a data-driven analysis to determine the signal processing and machine learning required to detect reduced mobility in individual leaflets.

METHODS

We use direct numerical simulations to describe hemodynamic differences in transvalvular flow in ascending aorta models with healthy and stenotic valves. A Cartesian-grid flow solver and a reduced-order valve model simulate the complex dynamics of blood flow and leaflet motion, respectively. The two-way fluid-structure interaction coupling is achieved using a sharp interface immersed boundary method.

RESULTS

From a dataset of 21 simulations, we show leaflets with reduced mobility result in large, asymmetric pressure fluctuations in their vicinity, particularly in the region extending from the aortic sinus to the sino-tubular junction (STJ). We train a linear classifier algorithm by correlating sinus and STJ pressure measurements on the stent surface to individual leaflet status. The algorithm was shown to have >90% accuracy for prospective detection of individual leaflet dysfunction.

CONCLUSIONS

We demonstrate that using only two discrete pressure measurements, per leaflet, on the TAV stent, individual leaflet status can be accurately predicted. Such a sensorized TAV system could enable safe and inexpensive detection of prosthetic valve dysfunction.

Mosquitoes buzz and fruit flies don't-a comparative aeroacoustic analysis of wing-tone generation

Crepuscular mosquitoes, which swarm in low light conditions, exhibit a range of adaptations including large aspect-ratio wings, high flapping frequencies and small stroke amplitudes that taken together, facilitate the generation of wing-tones that are well-suited for acoustic communication. In the current study, we employ computational aeroacoustic modeling to conduct a comparative study of wing-tone and flight efficiency in a mosquito (maleCulex) and a similar sized flying insect: a fruit fly (Drosophila). Based on this analysis, we show that pound-for-pound, a mosquito generates wing-tones that are a factor of about 3.4 times more intense than a fruit fly, and the mosquito is more efficient by a factor of about 3.7 in converting mechanical power into acoustic power. The wing-tones for the mosquito are also more tilted in the forward direction, a characteristic that would be more conducive for acoustic signaling during a mate chase. The simulation data also shows that the specific power (mechanical power over mean lift) of the mosquito is nearly equal to that of the fruit fly, indicating that the adaptations that facilitate wing-tone based communication in mosquitoes, do not seem to compromise their flight efficiency.

One size fits all?: A simulation framework for face-mask fit on population-based faces

The use of face masks by the general population during viral outbreaks such as the COVID-19 pandemic, although at times controversial, has been effective in slowing down the spread of the virus. The extent to which face masks mitigate the transmission is highly dependent on how well the mask fits each individual. The fit of simple cloth masks on the face, as well as the resulting perimeter leakage and face mask efficacy, are expected to be highly dependent on the type of mask and facial topology. However, this effect has, to date, not been adequately examined and quantified. Here, we propose a framework to study the efficacy of different mask designs based on a quasi-static mechanical model of the deployment of face masks onto a wide range of faces. To illustrate the capabilities of the proposed framework, we explore a simple rectangular cloth mask on a large virtual population of subjects generated from a 3D morphable face model. The effect of weight, age, gender, and height on the mask fit is studied. The Centers for Disease Control and Prevention (CDC) recommended homemade cloth mask design was used as a basis for comparison and was found not to be the most effective design for all subjects. We highlight the importance of designing masks accounting for the widely varying population of faces. Metrics based on aerodynamic principles were used to determine that thin, feminine, and young faces were shown to benefit from mask sizes smaller than that recommended by the CDC. Besides mask size, side-edge tuck-in, or pleating, of the masks as a design parameter was also studied and found to have the potential to cause a larger localized gap opening.

Computational insights of phytochemical-driven disruption of RNA-dependent RNA polymerase-mediated replication of coronavirus: a strategic treatment plan against coronavirus disease 2019

The current pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has raised global health concerns. RNA-dependent RNA polymerase (RdRp) is the prime component of viral replication/proliferation machinery and is considered to be a potential drug target against SARS-CoV-2. The present study investigated the anti-RdRp activity of phytochemicals against SARS-CoV-2 infection. Virtual ligand screening was carried out to determine the potent compounds against RdRp. Molecular docking and an MD Simulation study were employed to evaluate the spatial affinity of selected phytochemicals for the active sites of RdRp. Structural stability of target compounds was determined using root mean square deviation computational analysis and drug-like abilities were investigated using ADMET. Bond distances between ligand and receptor were marked to predict the strength of interaction. Aloe, azadirachtin, columbin, cirsilineol, nimbiol, nimbocinol and sage exhibited the highest binding affinities and interacted with active sites of RdRp, surpassing the ability of chloroquine, lamivudine, favipiravir and remdesivir to target the same. All the natural metabolites exhibited stable conformation during MD Simulation of 101 ns at 310 K. Kinetic, potential and electrostatic energy were observed to be least in the case of natural metabolites in comparison with synthetic analogues. Deviations and fluctuations were observed to be structurally least in target phytochemicals. Physiochemical and biological properties of these compounds further validated their drug-like properties. Non-bonded distance was found to be short enough to form hydrogen bonding or hydrophobic interactions, which revealed that these target compounds can strongly bind with RdRp. The study found potential phytochemicals to disrupt the replication domain of SARS-CoV-2 by hindering RdRp. We therefore anticipate that the current findings could be considered as valuable for the development of an efficient preventive/therapeutic expedient against COVID-19.

Use of impregnated catheters to decrease colonization rates in neonates - A randomized controlled pilot trial

OBJECTIVE

Nosocomial infections increase mortality and morbidity in preterm infants. Central venous line colonization is a major risk factor for the development of such infections. In adults and children, antibiotic and antimycotic impregnated catheters have been demonstrated to reduce colonization. However, recently published data showed no significant difference in bloodstream infection in neonates when an impregnated catheter was used. We investigated the effect of impregnation of percutaneously inserted micro-catheters (PICC) on colonization in preterm and sick term infants in our unit.

METHODS

Neonates were randomly assigned to receive either a standard (S-PICC; n = 34) or antibiotic and antimycotic impregnated (IP-PICC; n = 37) PICC. Catheters were placed and removed according to a standard procedure and subsequently examined by roll-out culture. The primary outcome was the rate of colonization defined as >15 colony-forming-units/ml. Additional outcomes were catheter associated or systemic infections.

RESULTS

The rate of colonization was lower in neonates who received an IP-PICC as compared to S-PICC (5.6% vs. 12.1% respectively; p = 0.42). However, the difference was not significant. In IP-PICC vs S-PICC, catheter related local infection (CRI) although lower was not statistically significant (2.9% vs. 6.1%; p = 0.60). We observed no difference in catheter related systemic infection (CR-SI) (0% vs. 3.1%, p = 0.48). The neonates whose catheters were colonized were predominantly of a lower gestational age (median 254/7, p = 0.05) and males (100%, p = 0.01). In addition, the median colony count in the colonized IP-PICC catheters was lower as compared to S- PICC group (53 vs 250, p = 0.06).

CONCLUSIONS

The use of antibiotic and antimycotic impregnated PICC-lines in neonates tended to decrease colonization rates in neonates in our centers but this difference was not significant. Lower gestational age and male sex are risk factors for catheter colonization.

A computational study of the hemodynamics of bioprosthetic aortic valves with reduced leaflet motion

We employ a reduced degree-of-freedom aortic valve model to investigate the flow physics associated with early-stage reduced leaflet motion in bioprosthetic aortic valves. The model is coupled with a sharp-interface immersed boundary based incompressible flow solver to efficiently simulate the fluid-structure interaction. A total of 19 cases of flow through aortic valves with varying degrees of reduced leaflet motion (RLM) are considered. The characteristics of the aortic jet and the consequent aorta wall loading patterns are analyzed. Our results show that asymmetric RLM tilts the aortic jet and leads to large reverse and recirculating flow regions downstream from leaflets with restricted mobility. The changes in flow patterns increase wall pressure and shear stress fluctuations, and result in asymmetric oscillating shear on the aorta wall. These findings have implications for auscultation based diagnosis of this condition as well as the health of the aorta.

Surgical Plating vs Closed Reduction for Fractures in the Distal Radius in Older Patients: A Randomized Clinical Trial

Importance

The burden of injury and costs of wrist fractures are substantial. Surgical treatment became popular without strong supporting evidence.

Objective

To assess whether current surgical treatment for displaced distal radius fractures provided better patient-reported wrist pain and function than nonsurgical treatment in patients 60 years and older.

Design, Setting, and Participants

In this multicenter randomized clinical trial and parallel observational study, 300 eligible patients were screened from 19 centers in Australia and New Zealand from December 1, 2016, until December 31, 2018. A total of 166 participants were randomized to surgical or nonsurgical treatment and followed up at 3 and 12 months by blinded assessors. Those 134 individuals who declined randomization were included in a parallel observational cohort with the same treatment options and follow-up. The primary analysis was intention to treat; sensitivity analyses included as-treated and per-protocol analyses.

Intervention

Surgical treatment was open reduction and internal fixation using a volar-locking plate (VLP). Nonsurgical treatment was closed reduction and cast immobilization (CR).

Main Outcomes and Measures

The primary outcome was the Patient-Rated Wrist Evaluation score at 12 months. Secondary outcomes were Disabilities of Arm, Shoulder, and Hand questionnaire score, health-related quality of life, pain, major complications, patient-reported treatment success, bother with appearance, and therapy use.

Results

In the 300 study participants (mean [SD] age, 71.2 [7.5] years; 269 [90%] female; 166 [81 VLP and 85 CR] in the randomized clinical trial sample and 134 [32 VLP and 102 CR] in the observational sample), no clinically important between-group difference in 12-month Patient-Rated Wrist Evaluation scores (mean [SD] score of 19.8 [21.1] for VLP and 21.5 [24.3] for CR; mean difference, 1.7 points; 95% CI -5.4 to 8.8) was observed. No clinically important differences were found in quality of life, wrist pain, or bother at 3 and 12 months. No significant difference was found in total complications between groups (12 of 84 [14%] for the CR group vs 6 of 80 [8%] for the VLP group; risk ratio [RR], 0.53; 95% CI, 0.21-1.33). Patient-reported treatment success favored the VLP group at 12 months (very successful or successful: 70 [89%] vs 57 [70%]; RR, 1.26; 95% CI, 1.07-1.48; P = .005). There was greater use of postoperative physical therapy in the VLP group (56 [72%] vs 44 [54%]; RR, 1.32; 95% CI, 1.04-1.69; P = 0.02).

Conclusions and Relevance

This randomized clinical trial found no between-group differences in improvement in wrist pain or function at 12 months from VLP fixation over CR for displaced distal radius fractures in older people.

Trial Registration

http://anzctr.org.au identifier: ACTRN12616000969460.

Acoustotactic response of mosquitoes in untethered flight to incidental sound

Mosquitoes are vectors for some of the most devastating diseases on the planet. Given the centrality of acoustic sensing in the precopulatory behavior of these vectors, the use of an exogenous acoustic stimulus offers the potential of interfering with the courtship behavior of these insects. Previous research on the acoustotactic response of mosquitoes has been conducted on tethered preparations using low-intensity sound stimuli. To quantify differences in acoustotactic responses between mosquitos of distinct sex and species, we examined the effects of incidental sound stimuli on the flight behavior of free-flying male vs. female Aedes aegypti and Anopheles gambiae mosquitoes. The key variables were sound frequency (100–1000 Hz) and intensity (67–103 dB, measured at 12.5 cm from the source), and the acoustotactic response was measured in terms of the relative increase in flight speed in response to the stimulus. The data show, for the first time, significant sex- and species-specific differences in acoustotactic responses. A. aegypti exhibited a greater response to sound stimulus compared to An. gambiae, and the response also extended over a larger range of frequencies. Furthermore, the males of both species displayed a greater acoustotactic response than females, with An. gambiae females exhibiting minimal response to sound.

Health and return to work in the first two years following road traffic injury: a comparison of outcomes between compensation claimants in Victoria and New South Wales, Australia

BACKGROUND

People who sustain road traffic injuries often have poor health outcomes. While outcomes are often worse in people with a compensation claim, especially in fault-based schemes versus no-fault schemes, few studies have directly compared outcomes across scheme types.

OBJECTIVE

To compare health and work outcomes between people who had no compensation claim, a fault-based claim, or "no-fault" transport or workers compensation claim after hospitalisation for a road traffic injury.

METHODS

Participants aged >=18 years admitted to hospital in New South Wales or Victoria for >24 hours were recruited in two separate prospective cohort studies (N=1,034). People who died or sustained minor or very severe injuries were excluded. Groups included Compulsory Third Party (fault-based, n=128), no-fault Transport Accident Commission (TAC; n=454) and workers compensation claimants (n=73), or no claim (n=226). Outcomes at six, 12- and 24-months post-injury included health [SF-12 Mental Component Score (MCS) and Physical Component Score (PCS)], and return to work for people working pre-injury. Multivariable mixed effects linear and logistic regressions, adjusting for demographic and injury covariates, examined differences in health and work outcomes between claimant groups, with fixed effects of time and random effects of participant ID.

RESULTS

Health status was better in people with a no-fault TAC claim (MCS: m=50.62, 95%CI:49.62,51.62; PCS: m=40.49, 95%CI:39.46,41.52) or no claim (MCS: m=49.99, 95%CI:49.62,51.62; PCS: m=44.36, 95%CI:43.00,45.72), than people with a workers compensation (MCS: m=45.73, 95%CI:43.46,48.00; PCS: m=38.94, 95%CI:36.59,41.30) or fault-based CTP claim (MCS: m=41.34, 95%CI:39.54,43.13; PCS: m=35.64, 95%CI:33.78,37.49). Relative to fault-based CTP claimants, the odds of returning to work were higher for people with no claim (AOR=6.84, 95%CI:1.73,27.05) but did not differ for no-fault TAC (AOR=1.21, 95%CI:0.36,4.05) or workers compensation claimants (AOR=0.83,95%CI: 0.17,3.99). While people with a fault-based CTP claim had poorer mental and physical health and return to work after injury, they showed greater improvements in mental health, and similar levels of improvement in physical health and work participation over time to the other groups.

CONCLUSION

The patterns of health and work across scheme types provide important insights against which we can contrast the effects of future scheme designs on client outcomes.

A mathematical framework for estimating risk of airborne transmission of COVID-19 with application to face mask use and social distancing

A mathematical model for estimating the risk of airborne transmission of a respiratory infection such as COVID-19 is presented. The model employs basic concepts from fluid dynamics and incorporates the known scope of factors involved in the airborne transmission of such diseases. Simplicity in the mathematical form of the model is by design so that it can serve not only as a common basis for scientific inquiry across disciplinary boundaries but it can also be understandable by a broad audience outside science and academia. The caveats and limitations of the model are discussed in detail. The model is used to assess the protection from transmission afforded by face coverings made from a variety of fabrics. The reduction in the transmission risk associated with increased physical distance between the host and susceptible is also quantified by coupling the model with available and new large eddy simulation data on scalar dispersion in canonical flows. Finally, the effect of the level of physical activity (or exercise intensity) of the host and the susceptible in enhancing the transmission risk is also assessed.

A Combined Randomised and Observational Study of Surgery for Fractures In the distal Radius in the Elderly (CROSSFIRE): a statistical analyses plan

Background

We are performing a combined randomised and observational study comparing internal fixation to non-surgical management for common wrist fractures in older patients. This paper describes the statistical analysis plan.

Methods/design

A Combined Randomised and Observational Study of Surgery for Fractures In the distal Radius in the Elderly (CROSSFIRE) is a randomised controlled trial comparing two types of usual care for treating wrist fractures in older patients, surgical fixation using volar locking plates and non-surgical treatment using closed reduction and plaster immobilisation. The primary aim of this comparative-effectiveness study is to determine whether surgery is superior to non-surgical treatment with respect to patient-reported wrist function at 12 months post treatment. The secondary outcomes include radiographic outcomes, complication rates and patient-reported outcomes including quality of life, pain, treatment success and cosmesis. Primary analysis will use a two-sample t test and an intention-to-treat analysis using the randomised arm of the study. Statistical analyses will be two-tailed and significance will be determined by p < 0.05. Sensitivity analyses will be conducted to assess for differences in intention-to-treat, per-protocol and as-treated analyses. Sensitivity analyses will also be conducted to assess selection bias by evaluating differences in participants between the randomised and observational study arms, and for bias relating to any missing data. An economic analysis will be conducted separately if surgery is shown to provide superior outcomes to a level of clinical significance.

Discussion

This statistical analysis plan describes the analysis of the CROSSFIRE study which aims to provide evidence to aid clinical decision-making in the treatment of distal radius fractures in older patients.

Trial registration

CROSSFIRE was approved by The Hunter New England Human Research Ethics Committee (HNEHREC Reference No: 16/02/17/3.04). Registered on 22 July 2016 with The Australian and New Zealand Clinical Trials Registry (ANZCTR Number; ACTRN12616000969460).

This manuscript is based on v.11 of the statistical analysis plan. A copy of v.11, signed by the chief investigator and the senior statistician is kept at the administering institution.

Computational modeling of swimming in marine invertebrates with implications for soft swimming robots

Marine flatworms (polyclads) employ a wide variety of body kinematics for swimming. In the current study, we employ computational fluid dynamics to study the hydrodynamics and swimming performance of a large variety of swimmers inspired directly from flatworms as well as two other marine invertebrates: Aplysia and Spanish dancers. The free-swimming performance is evaluated via two metrics: Froude efficiency and terminal swimming speed. The study examines the effect of the flapping of the lateral margins of the body as well as body undulation, which are used in various combinations by these animals to achieve swimming. The simulations suggest that a spanwise compact wake with distinct vortex ring structures is well correlated with a high swimming performance. We find that the addition of even a small magnitude of body undulation to lateral flapping results in significant changes in the wake patterns and noticeable improvements in the swimming performance compared to swimmers that employ only lateral flapping. Periodic body-bending synchronized with lateral flapping, as employed by the Spanish dancer, is found to be a very effective swimming gait. Some gaits that employ body undulations but no lateral flapping are found to generate high swimming speeds but with limited swimming efficiencies. Taken together, this study provides insights that could inform the design of swimming robots.

Phonons and oxygen diffusion in Bi2O3 and (Bi0.7Y0.3)2O3

We report investigation of phonons and oxygen diffusion in Bi2O3 and (Bi0.7Y0.3)2O3. The phonon spectra have been measured in Bi2O3 at high temperatures up to 1083 K using inelastic neutron scattering. Ab initio calculations have been used to compute the individual contributions of the constituent atoms in Bi2O3 and (Bi0.7Y0.3)2O3 to the total phonon density of states. Our computed results indicate that as temperature is increased, there is a complete loss of sharp peak structure in the vibrational density of states. Ab initio molecular dynamics simulations show that even at 1000 K in δ-phase Bi2O3, Bi-Bi correlations remain ordered in the crystalline lattice while the correlations between O-O show liquid like disordered behavior. In the case of (Bi0.7Y0.3)2O3, the O-O correlations broadened at around 500 K indicating that oxygen conductivity is possible at such low temperatures in (Bi0.7Y0.3)2O3 although the conductivity is much less than that observed in the undoped high temperature δ-phase of Bi2O3. This result is consistent with the calculated diffusion coefficients of oxygen and observation by quasielastic neutron scattering experiments. Our ab initio molecular dynamics calculations predict that macroscopic diffusion is attainable in (Bi0.7Y0.3)2O3 at much lower temperatures, which is more suited for technological applications. Our studies elucidate the easy directions of diffusion in δ-Bi2O3 and (Bi0.7Y0.3)2O3.

Flow physics and mixing quality in a confined impinging jet mixer

Due to their ability to provide efficient mixing at small scales, confined impinging jet mixers (CIJMs) are employed widely in nanoparticle assembly processes such as flash nanoprecipitation and flash nanocomplexation, which require rapid mixing. In this mixing device, two jets from opposite directions impinge directly on each other forming a thin shear layer that breaks down rapidly into small flow structures. This enables effective mixing of the species transported by each jet by drastically reducing the diffusion distance. In the present study, the mixing performance of a commonly used cylindrical CIJM is examined by direct numerical simulations. Analysis of the simulation results indicates that the interaction of the shear layer with the inner walls of the CIJM is critical in inducing a range of instabilities in the impinging jet flow. By examining flow structures, statistical quantities, and metrics, we have characterized and quantified the mixing quality of a binary mixture in the CIJM. Product uniformity in processes such as precipitation and complexation is expected to depend on the residence time of the constituents, and this quantity is also calculated and compared for the cases with different jet Reynolds numbers. The jet Reynolds numbers of Re = 200, 600, and 1000 are considered, and the simulation results show that the CIJM achieves very good mixing for the Re = 600 and Re = 1000 cases. It is also found that the Re = 600 case performs slightly better than the other cases in terms of uniformity of the residence time. These quantitative analyses offer useful insights into the mechanism of nanoparticle size control and uniformity afforded by the unique flow physics and mixing characteristics in the CIJMs.

Efficacy and safety comparison of combination of 0.04% tretinoin microspheres plus 1% clindamycin versus their monotherapy in patients with acne vulgaris: a phase 3, randomized, double-blind study

Background and objectives: There is an unmet need for topical treatments with good tolerability in management of acne vulgaris. The present study aimed to evaluate efficacy and safety of a novel tretinoin (microsphere, 0.04%) formulation in combination with clindamycin (1%) gel for treatment of acne vulgaris.Materials and methods: This phase 3 randomized, double-blind study included patients with moderate-to-severe acne. Patients were treated with tretinoin (microsphere, 0.04%) + clindamycin (1%) or one of the monotherapies (tretinoin, 0.025%; clindamycin, 1%). Key endpoints included percent change in lesion counts, and improvement in Investigator's Static Global Assessment (ISGA) score.Results: 750 patients were randomized (combination, n = 300; tretinoin and clindamycin, each n = 150). At week 12, reductions in inflammatory (77%), non-inflammatory (71%) and total lesions (73%) were significantly greater with combination treatment versus either monotherapy (p < .03). Proportion of patients rated 'clear' or 'almost clear' with ≥2-grade ISGA improvement was higher with combination (46%) versus monotherapies (p < .02). Adverse events occurred in 20 patients, most were mild-moderate; no deaths or serious adverse events were reported. The discontinuation rates due to adverse events with combination therapy were low (≤1%).Conclusion: The once-daily, microsphere-based formulation was generally tolerable with a positive impact on therapeutic outcomes and patients' compliance. ClinicalTrial Registration No.: CTRI/2014/08/004830.