Large Bed Research Articles

Simulation of heavy particles fluidized with non-Newtonian fluids

Aqueous solutions of very fine particles behave as non-Newtonian fluids and are used to fluidize heavy spherical particles creating large bed expansions and inhomogeneities similar to those observed in traditional fluidization of particles with Newtonian fluids. This study attempts to extend the validity of traditional computational fluid dynamics (CFD) models that are routinely used for gas-solids fluidization to non-Newtonian fluids. The modified model incorporates a shear-thinning power law viscosity for the non-Newtonian fluid and a recently published drag correlation derived from direct numerical simulation data of flow around randomly positioned spheres. This validation study compares numerical results obtained in 3D fluidized beds with two independent experimental bed porosity data sets for heavy steel and glass spherical particles. The current CFD results show a better agreement with experimental data obtained over a wide range of porosity and Reynolds number than a previously published semi-empirical correlation.

Design of effective heat transfer structures for performance maximization of a closed thermochemical energy storage reactor through topology optimization

This study addresses the need for heat transfer intensification in closed thermochemical energy storage reactors using topology optimization as a design approach. We introduce a novel topology optimization framework to simultaneously optimize fins geometry and amount of enhancer material while meeting specific discharge time, bed size, and bed porosity requirements. The proposed topology optimization framework is thoroughly tested by optimally designing innovative fin structures in a reference thermochemical storage reactor aimed at heat storage in industrial applications and operated with Strontium Bromide in the range 150-250 °C. The generated designs show performance improvement up to +286% compared to state-of-the-art designs. Our findings also indicate that the optimal amount of enhancer material varies significantly; large bed sizes with high packing factors maximize reactor energy density while highly packed reactive beds provide a larger amount of energy in fixed discharge times compared to less packed reactive beds. Finally, the benefits and limitations of the proposed topological optimization approach, as well as the extent to which the optimal designs found are generally applicable are thoroughly discussed to provide guidelines for configuring high-performing closed system thermochemical energy storage reactors.

Abstract 17427: Smaller Hospital Bed Size is Associated With Higher Mortality in Stanford Type A Aortic Dissection

Introduction: The National Inpatient Sample (NIS) database stratifies hospital bedsize according to the number of hospital beds, urban or rural, and teaching or non-teaching hospital. Larger hospital bed size stratified by these criteria has been associated with better patient care and surgical outcomes in some instances. This study aimed to examine the effect of hospital bed size on perioperative outcomes in Type A Aortic Dissection (TAAD). Methods: Patients who underwent TAAD repair were identified in the NIS from Q4 2015-2020 by ICD10-CM/PCS. NIS stratifies hospital bed size into small, medium, and large, rural vs urban, and teaching status. Patients were stratified into two cohorts: small/medium and large. Significant preoperative differences were present between groups; thus, multivariable logistic regressions were performed to compare the surgical outcomes (in-hospital). Adjusted preoperative variables included sex, age, race, socioeconomic status, comorbidity, primary payer status, hospital characteristics, length of stay (LOS), days from admission to operation, and total hospital charge were compared. Result: There were 1,106 and 3,752 cases with small/medium and large bed sizes, respectively, identified in the NIS database. Among patients admitted to small/medium bed size hospitals, there was higher mortality (17.27% vs 14.37%, aOR=1.32, 95% CI 1.09-1.60, p<0.01), but shorter LOS and lower cost compared to larger hospitals (Table). There was no difference in morbidities (Table). Conclusion: Marked higher mortality is associated with admission to smaller hospital bed sizes among patients with TAAD, which may in turn decrease the average LOS and cost. Given that a significant percentage of patient are already being transferred out of the initial hospital and small/medium hospital size is associated with higher mortality, centralization of care in centers of excellence may decrease the high mortality associated with TAAD.

Abstract 14977: Radial Artery Usage Rate Differs in Hospital Types in Coronary Artery Bypass Graft Surgery: An Insight Into National Inpatient Sample

Introduction: In coronary artery bypass grafting (CABG), the left internal mammary artery (LIMA) may not be utilized, and a secondary conduit is chosen to treat coronary artery disease. Radial artery (RA) and greater saphenous vein (GSV) are both viable secondary conduits to, although RA grafting is associated with higher patency and superior long-term survival. This study aimed to compare the rate of RA graft usage in CABG among different hospital types. Methods: Patients received CABG between Q4 2015-2020 were extracted from National Inpatient Sample (NIS) based on ICD10-PCS. Patients less than the age of 40 were excluded for congenital heart defects. Preoperative variables included sex, age, race and ethnicity, socioeconomic status (SES), Elixhauser comorbidities, and hospital characteristics. The rate of RA versus GSV usage were compared with respect to hospital location/teaching status and bed sizes, while all preoperative variables besides the variable of interest were adjusted by multivariable analysis. Results: There were 56,318 CABG cases identified with 11,708 RA and 44,610 GSV grafting. RA grafting usage was lower in rural hospitals (aOR 0.59, p<0.01), urban private practice (aOR 0.69, p<0.01), and hospitals with large bed sizes (aOR 0.91, p<0.01) while the rate is higher in urban teaching hospitals (aOR 1.50, p<0.01) and hospitals with medium bed sizes (aOR 1.14, p<0.01). Conclusion: This study reveals different RA graft usage for CABG among different hospital types. RA harvest can be more time consuming and resource intensive than GSV harvest. Increased familiarity overcoming these obstacles might increase RA graft usage.

Abstract 13017: National Characteristics and Outcomes of Adults With Pulmonary Embolism Undergoing Catheter Directed Thrombolysis Compared to Systemic Tissue Plasminogen Activator

Introduction: Catheter Directed Thrombolysis (CDT) and systemic tissue plasminogen activator (tPA) are commonly used interventions for pulmonary embolism (PE). We aim to compare these two procedures. Methods: Cases of pulmonary embolism in adults were used for our study from the National Inpatient Sample (2016-2020). We compared the characteristics and outcomes of patients undergoing CDT vs. systemic tPA <24 hours after hospitalization. Results: We found 16675 cases of PE, with 9130 (54.8%) patients undergoing tPA and 7545 (45.2%) needing CDT. Compared to tPA cases, a lower rate of weekend admission was seen in patients undergoing CDT. Both groups consisted of Whites and were covered primarily by Medicare. Most admissions took place in urban teaching centers, with large bed sizes and in the southern regions of the US. Furthermore, CDT patients were older (mean age 56.2 vs. 52.1 years), involving more patients with hypertension and obesity. However, CDT cases had fewer patients with diabetes, peripheral vascular disease, chronic kidney disease, prior stroke, and drug abuse and reported a lower mean Charlson Comorbidity Index(CCI) score(table 1). tPA patients also had higher rates of atrial fibrillation, ventricular fibrillation, and atrial flutter. Overall, 5.9% of patients undergoing tPA died, while 1.8% died in the CDT cohort (aOR death in tPA 2.604 vs. CDT, 95% CI 2.033-3.335, p<0.01). A higher mortality rate within the first week of hospitalization was also seen in the tPA group (figure 1). tPA cohort also reported higher odds of acute kidney injury(AKI) (aOR 1.484, 95% CI 1.364-1.615, p<0.01) and cardiogenic shock (aOR 3.588, 95% CI 2.990-4.304, p<0.01). Finally, tPa patients had a lengthier stay. Conclusions: CDT cases showed lower mortality during the first week of the procedure. Differences in comorbidities exist between the two groups. Further research exploring additional factors may help address current protocols to improve long-term outcomes.

Lacustrine sedimentation by powerful storm waves in Gale crater and its implications for a warming episode on Mars

This investigation documents that the Rugged Terrain Unit, the Stimson formation, and the Greenheugh sandstone were deposited in a 1200 m-deep lake that formed after the emergence of Mt. Sharp in Gale crater, Mars, nearly 4 billion years ago. In fact, the Curiosity rover traversed on a surface that once was the bottom of this lake and systematically examined the strata that were deposited in its deepest waters on the crater floor to layers that formed along its shoreline on Mt. Sharp. This provided a rare opportunity to document the evolution of one aqueous episode from its inception to its desiccation and to determine the warming mechanism that caused it. Deep water lacustrine siltstones directly overlie conglomerates that were deposited by mega floods on the crater floor. This indicates that the inception phase of the lake was sudden and took place when flood waters poured into the crater. The lake expanded quickly and its shoreline moved up the slope of Mt. Sharp during the lake-level rise phase and deposited a layer of sandstone with large cross beds under the influence of powerful storm waves. The lake-level highstand phase was dominated by strong bottom currents that transported sediments downhill and deposited one of the most distinctive sedimentological features in Gale crater: a layer of sandstone with a 3 km-long field of meter-high subaqueous antidunes (the Washboard) on Mt. Sharp. Bottom current continued downhill and deposited sandstone and siltstone on the foothills of Mt. Sharp and on the crater floor, respectively. The lake-level fall phase caused major erosion of lacustrine strata that resulted in their patchy distribution on Mt. Sharp. Eroded sediments were then transported to deep waters by gravity flows and were re-deposited as conglomerate and sandstone in subaqueous channels and in debris flow fans. The desiccation phase took place in calm waters of the lake. The aqueous episode we investigated was vigorous but short-lived. Its characteristics as determined by our sedimentological study matches those predicted by an asteroid impact. This suggests that the heat generated by an impact transformed Mars into a warm, wet, and turbulent planet. It resulted in planet-wide torrential rain, giant floods on land, powerful storms in the atmosphere, and strong waves in lakes. The absence of age dates prevents the determination of how long the lake existed. Speculative rates of lake-level change suggest that the lake could have lasted for a period ranging from 16 to 240 Ky.

Differences in Bacterial Growth and Mortality between Seagrass Meadows and Adjacent Unvegetated Areas

A seagrass meadow is one of the most important ecosystems around the world, both economically and ecologically. An important feature of this ecosystem is the presence of large coastal seagrass beds, which dominate the primary production and contribute to the secondary productivity of the ecosystem. The microbial loop (consuming bacterial biomass by grazers and using seagrass-derived detritus by bacteria) may be an important mechanism for transferring seagrass-derived organic matter to aquatic food chains. The goal of this study is to gain a better understanding of how bacterial growth and mortality (grazing and viral lysis rates) differ in unvegetated meadow habitats and seagrass habitats. According to this study, DOC levels were higher in seagrass habitats (1685 g L−1) than in unvegetated water surroundings. The instantaneous growth rate of bacteria in seagrass habitats was 2.05 d−1, higher than that of unvegetated water. In a seagrass environment during the summer, we have found that viral lysis and grazing both result in similar mortality rates of bacteria during the summer season. It has been found, however, that bacterial production is controlled by the availability of resources (bottom-up control) in adjacent unvegetated waters, and is thus cycled internally within the bacteria–virus–DOC loop within those waters.

Impact of pulmonary hypertension on outcomes of influenza pneumonia patients: A nationwide analysis

Background: Pulmonary hypertension can be a significant cause of morbidity and mortality for influenza pneumonia (IP) patients. We performed analysis from the multicentric National Inpatient Sample (NIS) datasets to study the influence of disorders of pulmonary hypertension on the outcomes in IP patients. Methods: We used NIS 2016–2019 to identify IP hospitalizations (between 22–90 years of age) and divided them into with and without pulmonary hypertension (herein PHDPC). We analyzed for differences in demographics, primary (all-cause mortality) and other secondary outcomes. Results: Of 353,460 IP hospitalizations, 6.5% had PHDPC. The PHDPC cohort had more elderly, females, African Americans, and Medicare enrollees predominantly with more hospitalizations to large bed sizes and urban teaching hospitals, and higher cardiovascular comorbidities than non-PHDPC cohort. PHDPC had higher primary outcomes for in-hospital mortality (8.9% vs. 5.8%, adjusted OR 1.4, 95% CI: 1.21–1.61). PHDPC also had higher secondary outcomes for sepsis, septic shock, cardiogenic shock and need for mechanical ventilation, prolonged ventilation, hospital resource utilization for longer mean length of stay, mean hospitalization cost, transfer to other facilities or need for home health care, and high risk for 30-day readmission than the non-PHDPC cohort. Conclusions: With our study, we provide contemporary data for the outcomes of IP inpatients with pulmonary hypertension and depict worse outcomes for mortality, complications, and hospital resource utilization. Although our study does not include stratification for vaccination status for the outcome, primary care physicians, cardiologists, and pulmonologists should pro-actively educate patients on preventive strategies during the flu season.

SAT111 Temporal Trends In Patients Hospitalized With Diabetic Ketoacidosis And Associated Outcomes: Insights From The National Inpatient Sample

Abstract Disclosure: M. Chaudhary: None. J. Jung: None. A. Farooq: None. J. Heersink: None. Background: Patients hospitalized with Diabetic Ketoacidosis (DKA) exhibit increased risk for mortality and morbidity. Previous work has illustrated concerns for DKA incidence increasing further highlighting the burden it may present to the US healthcare system. We aim to demonstrate the current baseline characteristics in hospitalized DKA patients and to identify and stratify risk factors that lend to deleterious patient outcomes. Methods: Patient data was collected for years 2011-2018 from the National Inpatient Sample (NIS) using International Classification of Disease-Revision Codes (ICD-9 and 10). We selected patients hospitalized with a principal diagnosis of DKA with ICD Coding. Multivariate logistic regression was used to determine adjusted odds ratios (AOR). Mann-Whitney U testing was utilized to calculate mean differences in age, length of stay (LOS), and total hospital charges. Additionally temporal trends were tabulated with linear regression models to determine any significant changes over time in select risk factors and outcomes. Results: A total of 313,608 patients were included in our data analysis. Self-pay patients had a 28.3% (CI 1.020-1.613, P<0.05) increase in mortality rate compared to Medicare payers. Asians had 60.5% (CI 1.039-2.479, P<0.05) increased risk of mortality compared to Caucasians. Increased mortality rates were seen in patients with following comorbid conditions: ESRD (149%) (CI 1.986-3.140, P<0.05), Obesity (70.5%) (CI 1.425-2.040, P<0.05)and CAD (25%) (CI 1.057-1.478, P<0.05). Females with DKA had a decreased risk of mortality by 21%(Cl 0.697-0.894, P<0.05). Patients in the highest quartile median zip code income had a decreased mortality risk of 18.7% compared to patients in the 1st quartile (add the P value). There was a 25.6% (CI 1.069-1.505, P<0.05) decreased mortality rate in hospitals with large bed size and a 30.8% decreased mortality rate in urban located teaching hospitals (CI 1.062-1.612, P<0.05). We observed decreases in LOS and over time P<0.05 and increase in Hospital Charges over time P<0.05. Conclusion: We observed correlation between socio-economic and demographic factors and mortality outcomes in patients hospitalized with DKA. Based on our analysis, we found patients with ESRD, Obesity, and CAD to exhibit the highest mortality risk. Decreased LOS over time may exhibit incremental improvements in quality of care of patients hospitalized with DKA and would beget further analysis in comparison with available longitudinal studies with more granular data. Increased total charges may represent an increasing patient complexity and this warrants further investigation. Further research in community-based hospital settings is needed and it is important to note that targeted prevention measures, such as diabetes education, may help prevent life-threatening diabetic complications such as DKA from arising. Presentation: Saturday, June 17, 2023

Bidisperse beds sheared by viscous fluids: Grain segregation and bed hardening

When a granular bed is sheared by a fluid that flows above a critical limit, it undergoes a complex motion that varies along time: it can contain fluid- (bedload) and solid-like (creep) regions, being prone to strain hardening and, in the case of polydispersity, segregation. In this paper, we investigate experimentally the short- and long-time evolution of a bidisperse bed sheared by a viscous liquid. Different from previous experiments, the density ratio between grains and fluid is 2.7, close to values found in rivers and oceans. We show the existence of diffusive, advective, and constrained regions, that most of segregation occurs during the very first stages of the flow, and that bed hardening becomes stronger while bedload and creep weaken along time. We obtain the segregation rates, their evolution along time, their variation with the applied shearing, and the time evolution of creeping and bedload. Finally, we propose characteristic times for the segregation of large particles and bed hardening. Our results shed light on the complex motion of sheared beds existing in nature, such as river beds and creeping lands.

Stability and probabilistic assessment of a large asymmetric bedding slope with a weak interlayer.

The mining of open-pit mines has a significant influence on the surrounding ecological environment and safety. Once the slope of an open pit is unstable, it will bring extremely severe disasters to the surrounding environment. The south slope of the Fushun West open-pit mine is a large bedding slope with weak interlayer and asymmetrical features between the eastern and western regions. The different deformation mechanisms are worth further discussion, and the deformation mechanism of the eastern region needs to be systematically investigated. In this study, a comprehensive method combining a numerical model, the limit equilibrium method, and a probabilistic approach is used. The different deformation mechanisms of the slope are explored. Thereafter, the sensitivity of the geometric and mechanical parameters of the slope is determined. Finally, the probability of failure (PF) and slope stability are evaluated. The results illustrate that the difference in geological characteristics and constraint conditions is the fundamental reason for the difference in deformation features of the slope. The sensitivity analysis results show that the friction angle of the weak layer exhibits the most sensitivity and that the unit weight is irrelevant to the slope stability. Taking the friction angle of the weak layer as a variable, when thethickness of the basalt layer is less than 140 m and the height of the slope is more than 360 m, the PF of the slope reaches a high value. When the inclination of the weak layer exceeds 30°, the PF of the slope increases to a high value. When the Ru coefficient exceeds 0.2, the slope presents a high PF. The results illustrate that decision-makers should pay attention to the strength degradation, transitional mining of the basalt layer, and establish a good drainage system. The comprehensive method can also provide an effective way to assess the stability and PF of similar large-scale bedding slopes under complex geological conditions.

Bubbling fluidized bed co-combustion and co-gasification of sewage sludge with agricultural residues with a focus on the fate of phosphorus

In this work, the fate of the ash-forming elements during bubbling fluidized bed combustion and gasification of P-rich sewage sludge (SS) and mixtures with either Si-K-rich wheat straw (WS) or K-Ca-rich sunflower husks (SH) were investigated. The focus of the study was assessing the feasibility of using fuel blends in fluidized bed systems and potential P recovery from the resulting ashes. The used fuels were pure SS and mixtures including 90 wt.% WS (WSS) and 85 wt.% SH (SHS). The analyzed operating conditions were combustion (930–960 °C, λ: 1.2–1.5) and gasification (780–810 °C, λ: 0.4–0.7) in a 5 kW bench-scale reactor. Residual ash and char fractions were collected from different parts of the 5 kW bubbling fluidized bed (bed, cyclone, filter) and analyzed by CHN, SEM/EDS, XRD, and ICP-AES.The conversion of the fuel mixtures achieved a steady state under the used process conditions except for the combustion of WSS, which led to the formation of large bed agglomerates with the bed material. The morphology of ash samples after combustion showed that SS fuel pellets mostly maintained their integrity during the experiment. In contrast, the ash and char particles from fuel mixtures were fragmented, and larger quantities were found in the cyclone, the filter, or on interior reactor surfaces. The fate of P was dominated by crystalline Ca-dominated whitlockites in all ash fractions, partially including K for the fuel mixtures SHS and WSS. 76–81 % of ingoing P was found in the bed residue after combustion and gasification of the SS-fuel. After conversion of the fuel mixtures SHS and WSS, the share was lower at 22–48 %, with larger shares of P in the entrained fractions (25–34 %). The quantity of identified crystalline compounds was lower after gasification than combustion, likely due to the limited interaction of ash-forming elements in the residual CHN matrix. Altogether, the results show that fuel mixtures of sewage sludge with agricultural residues could expand the fuel feedstock and enable P recovery. This may be used in the fuel and process design of upscaled fluidized bed processes or systems employing both combustion and gasification.

Measurements of tidal flow variability in Ramsey Sound, Pembrokeshire

The nature of the flow at in-stream tidal energy sites is particularly important for predicting array and device performance, and also for operations and maintenance planning. Previous developers have reported issues such as the choice of vessel, cost of operations, and the limits of operation of deployment vessels. The dynamics of the flow around slack water has been of particular interest at Ramsey Sound in Pembrokeshire (UK) for planning the recovery of an existing turbine, the Tidal Energy Limited ‘Deltastream’.
 This research presents flow characteristics of Ramsey Sound, based on analysis of Acoustic Doppler Current Profiler (ADCP) measurements and tide gauge data from the nearby Standard Port of Milford Haven. The ADCP was located approximately 300 m across the channel, at the northern end of the channel, where the channel width was 1200 m and the mean depth was approximately 33 m. The flow dynamics were examined specifically to look at times potentially suitable for offshore operations Two weeks of data were used in the analysis, spanning a complete spring-neap cycle.
 Results demonstrate that flow velocities exhibited clear asymmetry, with stronger flows on the northerly directed flood tide than on the ebb. There was considerable variation in the measured current speed around the time of the maximum, suggesting large scale bed feature generated turbulence. The flood (northerly) current maximum was approximately in phase with high water at Milford Haven. Cross correlation indicated that the flow generally led the elevation by 20 minutes. In contrast to the expected theory, the current strength at mid-depth was stronger than at the surface on the maximum flood tide. The maximum flow speed in the tide was reasonably predictable from the tide range at Milford. A threshold-based analysis of the ADCP measurements allowed the duration of slow-moving water to be identified for operation planning.
 Operations and planning in light of sound understanding of hydrodynamics at tidal energy sites is critical for future economic success of the tidal energy sector. The results shown here from an ADCP deployment in Ramsey Sound have shown the capability to give useful tools for planning recovery operations.

Note on seabed shear stress beneath bichromatic and bidirectional waves for large bed roughness

Note on seabed shear stress beneath bichromatic and bidirectional waves for large bed roughness

Short‐term effects on Unionid mussel density and distribution before and after low‐head dam removal in northern New York

AbstractUnionid mussel populations have declined in many environments, particularly those that were altered by human activities such as dam construction and removal. The Fort Covington Dam blocked the Salmon River in northern New York upriver of its confluence with a smaller tributary, the Little Salmon River. This dam was removed in 2009. My study compared the mean ranked density of mussels in both rivers for the pre‐removal period (2005–2008) to the post‐removal period (2009–2012) with special attention to Lampsilis cariosa and Margaritifera margaritifera. Systematic sampling was used at six riffles and double sampling at four glides divided between the Salmon and Little Salmon rivers from 2005 through 2012. The Little Salmon River served as a control. Mean ranked adult mussel density was not significantly different between the two rivers in the pre‐removal period but was significantly greater in the Little Salmon River after dam removal. Living mussels of 13 species were collected dominated by Elliptio complanata. Dam removal did not affect sediment sorting, porosity, water chemistry, or mussel species distribution. Rapid dewatering of the reservoir led to stranding and death of mussels in the reservoir and in the adjacent ponds. Increased water velocity, exacerbated by rain, mobilized sediment that buried a potentially large mussel bed downstream of the dam where Lampsilis cardium and L. cariosa were abundant, which showed little recovery by 2013.

Lymph node evaluation for endometrial hyperplasia: a nationwide analysis of minimally invasive hysterectomy in the ambulatory setting

BackgroundGiven the possibility of occult endometrial cancer where nodal status confers important prognostic and therapeutic data, role of lymph node evaluation at hysterectomy for endometrial hyperplasia is currently under active investigation. The objective of the current study was to examine the characteristics related to lymph node evaluation at the time of minimally invasive hysterectomy when performed for endometrial hyperplasia in an ambulatory surgery setting.MethodsThe Healthcare Cost and Utilization Project's Nationwide Ambulatory Surgery Sample was retrospectively queried to examine 49,698 patients with endometrial hyperplasia who underwent minimally invasive hysterectomy from 1/2016 to 12/2019. A multivariable binary logistic regression model was fitted to assess the characteristics related to lymph node evaluation at hysterectomy and a classification tree model with recursive partitioning analysis was constructed to examine the utilization pattern of lymph node evaluation.ResultsLymph node evaluation was performed in 2847 (5.7%) patients. In a multivariable analysis, (i) patient factors with older age, obesity, high census-level household income, and large fringe metropolitan, (ii) surgical factors with total laparoscopic hysterectomy and recent year surgery, (iii) hospital parameters with large bed capacity, urban setting, and Western U.S. region, and (iv) histology factor with presence of atypia were independently associated with increased utilization of lymph node evaluation at hysterectomy (all, P < 0.05). Among those independent factors, presence of atypia exhibited the largest association for lymph node evaluation (adjusted odds ratio 3.75, 95% confidence interval 3.39–4.16). There were 20 unique patterns of lymph node evaluation based on histology, hysterectomy type, patient age, year of surgery, and hospital bed capacity, ranging from 0 to 20.3% (absolute rate difference, 20.3%).ConclusionLymph node evaluation at the time of minimally invasive hysterectomy for endometrial hyperplasia in the ambulatory surgery setting appears to be evolving with large variability based on histology type, hysterectomy modality, patient factors, and hospital parameters, warranting a consideration of developing clinical practice guidelines.

Experimental Observations of Bedload Tracer Movement: Effects of Mixed Particle Sizes and Bedforms

AbstractPredicting the transport of bedload tracer particles is a problem of significant theoretical and practical interest. Yet, little understanding exists for transport in rivers in the presence of bedforms, which may trap grains and thereby influence travel distance. In a series of flume experiments with a sandy gravel bed in a large experimental flume, bed elevation and tracer travel distances were measured at high resolution for a range of discharges. As discharge increased, bedform height increased and bedform length decreased, increasing bedform steepness. For all tracer sizes and flow conditions, bedforms act as primary controls on the tracer travel distances. Bedform trapping increases linearly with the ratio of bedform height to tracer grain size, with 50% trapping efficiency for a ratio of two and 90% trapping efficiency for a ratio of four. A theoretical model based on the extended active layer formulation for sediment transport is able to capture much of the distribution of measured travel distances for all tracer sizes and discharges, providing a first connection between tracer transport theory and bedform trapping and indicating normal diffusion of tracers at relatively small timescales. Variable bedform geometry can influence trap efficiency for individual bedforms and the theoretical model can help identify “preferential trapping” conditions. The distribution of tracer travel distances for a mixture of grain sizes and variable discharge, as expected in natural rivers, displays heavy tail characteristics.

Abstract 723: Positional Transcriptomics Defines Regionally Restricted Sex-specific Differences Of The Vessel Wall

Cardiovascular diseases (CVDs) remain the leading causes of morbidity and mortality for both men and women, globally. Abdominal aortic aneurysm (AAA) represents a class of CVD with significant sex-stratification as disease burden is higher in males, but outcome of disease is poorer in females. Establishment of AAA is a complex process, defined by the interaction of multiple environmental influences and host regional vascular heterogeneity. While is it is known that many factors including developmental origin, local cellular diversity and regional bio-mechanical forces contribute to vascular bed specialization, the exact contribution of biological sex in vascular heterogeneity remains unknown. To elucidate the molecular contribution of sex to vascular heterogeneity of large arterial beds we performed single cell sequencing from cells isolated from 4 distinct anatomic locations of both male and female young adult mice: the carotid arteries, aortic arch, thoracic and abdominal aorta. Using this approach, we identified anatomic sex-invariant gene signatures as well as regional sex-specific gene signatures in vascular smooth muscle cells (vSMC) and used immunohistochemistry to validate these findings. Surprisingly, prominent regional-sex dependent differences were observed in vSMCs of the thoracic and abdominal aorta, consistent with sex-specific burden of aneurysm in these regions. From these sex-specific regionally restricted vSMC signatures, we identified several enriched signature genes that are likely contributors in the regulation of AAA development in mice and humans.

Hand and Wrist Amputation: A Demographic Analysis Using the National Inpatient Sample.

Traumatic hand and wrist amputations are rare but debilitating injuries. Surgical replantation of the hand provides a unique alternative to revision surgery but requires appropriate access to necessary medical resources. This study aims to understand the national practice of replantation of traumatic hand amputation and to determine whether disparities exist in accessing surgical treatment. International Classification of Diseases, 10th Revision codes for replantation and revision amputation surgeries were used to gather data from the National Inpatient Sample from 2016 to 2019. Summary statistics were calculated on demographic, hospital, and outcome variables, with subanalysis performed for effect on replantation and revision rates. Seventy-two patients were identified. The average patient was 35 years old with a strong male predominance (90%). The racial distribution of the cohort roughly mirrored the demographic proportions of race in the US population. Fifteen (21%) patients underwent replantation. This rate was similar between sexes, races, and income brackets. Hand replantation was primarily performed at large bed size (87%), private not-for-profit (73%), and urban teaching hospitals (94%). The most common insurance status for these patients was private, followed by Medicaid, Medicare, and self-pay. Forty-seven patients underwent revision amputation (65%) with no association between demographic characteristics. The patients remained hospitalized for significantly longer periods (P = .0188) and paid significantly more (P = .0014) if replanted. The patients were most frequently discharged home (65%), followed by skilled nursing facilities (18%). This study describes the current state of hand amputation management and finds no evidence of sociodemographic factors influencing the surgical care provided.

D99. Hand and Wrist Amputation: A Demographic Analysis Using the National Inpatient Sample

PURPOSE: Traumatic hand and wrist amputations are rare but debilitating injuries. Surgical replantation of the hand provides a unique alternative to revision surgery but requires appropriate access to necessary medical resources. This study aims to understand how sociodemographic barriers impact the replantation rate of traumatic hand amputation on a national level. METHODS: ICD-10 codes for replantation and revision amputation surgeries were used to gather data from the National Inpatient Sample from 2016-2019. Summary statistics were calculated on demographic, hospital, and outcome variables with sub-analysis performed for effect on replantation and revision rates. RESULTS: 72 patients were identified. The average patient was 37 years old with a strong male predominance (90%). Racial distribution of the cohort roughly mirrored the demographic proportions of race in the US population. 17 (24%) patients underwent replantation. This rate was similar between sexes (p = 0.348), races (p = 0.715), and income brackets (0.620). Hand replantation was primarily performed at large bed size (87%), private not-for-profit (73%), and urban teaching hospitals (100%). The most common insurance status for these patients was private, followed by Medicaid, Medicare, then self-pay. 47 patients underwent surgical revision (65%) with no association between demographic characteristics. Patients remained hospitalized for 11 days on average, regardless of the surgery received. Patients were most frequently discharged home (65%) followed by skilled nursing facilities (18%). CONCLUSION: This study investigates the current state of hand amputation management. With this information, surgeons may be more equipped to mitigate the impact of sociodemographic characteristics on appropriate treatment.