Using Data Science Tools to Reveal and Understand Subtle Relationships of Inhibitor Structure in Frontal Ring-Opening Metathesis Polymerization.

The rate of frontal ring-opening metathesis polymerization (FROMP) using the Grubbs generation II catalyst is impacted by both the concentration and choice of monomers and inhibitors, usually organophosphorus derivatives. Herein we report a data-science-driven workflow to evaluate how these factors impact both the rate of FROMP and how long the formulation of the mixture is stable (pot life). Using this workflow, we built a classification model using a single-node decision tree to determine how a simple phosphine structural descriptor (Vbur-near) can bin long versus short pot life. Additionally, we applied a nonlinear kernel ridge regression model to predict how the inhibitor and selection/concentration of comonomers impact the FROMP rate. The analysis provides selection criteria for material network structures that span from highly cross-linked thermosets to non-cross-linked thermoplastics as well as degradable and nondegradable materials.

Artificial Intelligence for Real-Time Prediction of the Histology of Colorectal Polyps by General Endoscopists.

BACKGROUND: Real-time prediction of histologic features of small colorectal polyps may prevent resection and/or pathologic evaluation and therefore decrease colonoscopy costs. Previous studies showed that computer-aided diagnosis (CADx) was highly accurate, though it did not outperform expert endoscopists. OBJECTIVE: To assess the diagnostic performance of histologic predictions by general endoscopists before and after assistance from CADx in a real-life setting. DESIGN: Prospective, multicenter, single-group study. (ClinicalTrials.gov: NCT04437615). SETTING: 6 centers across the United States. PARTICIPANTS: 1252 consecutive patients undergoing colonoscopy and 49 general endoscopists with variable experience in real-time prediction of polyp histologic features. INTERVENTION: Real-time use of CADx during routine colonoscopy. MEASUREMENTS: The primary end points were the sensitivity and specificity of CADx-unassisted and CADx-assisted histologic predictions for adenomas measuring 5 mm or less. For clinical purposes, additional estimates according to location and confidence level were provided. RESULTS: The CADx device made a diagnosis for 2695 polyps measuring 5 mm or less (96%) in 1252 patients. There was no difference in sensitivity between the unassisted and assisted groups (90.7% vs. 90.8%; P = 0.52). Specificity was higher in the CADx-assisted group (59.5% vs. 64.7%; P < 0.001). Among all 2695 polyps measuring 5 mm or less, 88.2% and 86.1% (P < 0.001) in the CADx-assisted and unassisted groups, respectively, could be resected and discarded without pathologic evaluation. Among 743 rectosigmoid polyps measuring 5 mm or less, 49.5% and 47.9% (P < 0.001) in the CADx-assisted and unassisted groups, respectively, could be left in situ without resection. LIMITATION: Decision making based on CADx might differ outside a clinical trial. CONCLUSION: CADx assistance did not result in increased sensitivity of optical diagnosis. Despite a slight increase, the specificity of CADx-assisted diagnosis remained suboptimal. PRIMARY FUNDING SOURCE: Olympus America Corporation served as the clinical study sponsor.

Americas Hepato-Pancreato-Biliary Association HPB Ultrasound and Advanced Technology post-graduate course: Overview and review.

Background: Americas Hepato-Pancreato-Biliary Association (AHPBA) established the Hepato-Pancreato-Biliary (HPB) ultrasound (US) and Advanced Technology Post-Graduate Course in 2012 in response to a perceived gap in training and practice. Methods: The HPB US and Advanced Technology Post-Graduate Course consists of both didactic and hands-on skills sessions. The didactic sessions are divided into foundational, organ-focused, and application content. Hands-on sessions are constructed to immediately practice skills in the simulation setting which were taught during the didactic sessions. Course participant demographic data (practice location and practice type) and participant evaluations were reported. Results: Since the first course in 2012, 298 participants have taken the post-graduate course. Most participants reported the content quality, delivery effectiveness, and practice relevance to be either excellent or above average (93.6 %, 91.1 %, 93.6 %, respectively). Participants' motivations to take the course included to enhance skills, knowledge, to incorporate US into practice, or to obtain formal training or qualification/certification, or to teach. Conclusion: The HPB US and Advanced Technology Post-Graduate Course has filled a gap in HPB US training for practicing HPB surgeons. The annual course has been well-received by participants (Kirkpatrick Level 1 Program Evaluation) and will continue to fill the gap in training in operative US for the HPB surgeon. Key message: Americas Hepato-Pancreato-Biliary Association established the HPB Ultrasound and Advanced Technology Post-Graduate Course in 2012. The Course has been well-received by participants and will continue to address a gap in surgical HPB training.

Ultrasound scanning techniques.

Background: Ultrasound is an essential tool for the hepatobiliary and pancreatic surgeon. Methods: This review focuses on transabdominal, open intraoperative, and laparoscopic ultrasonography of the liver, biliary tract, and pancreas. The goal is to obtain optimal ultrasound images through an understanding of the equipment setup, transducer (probe) selection, terminology, and general scanning principles. Outlined is a structured, standardized approach necessary to obtain complete information when doing intraoperative ultrasound. When done by the surgeon, the goal of the examination typically is to answer a question or questions through a focused rather than a comprehensive diagnostic examination. Finally, presented are the details of techniques specific to scanning each of the major organs. Results: A structured, standardized ultrasound scanning approach provides for optimal image acquisition. It allows one to develop standardized views of common structures resulting in "pattern recognition," making learning and interpreting images easier. A standardized approach ensures a complete ultrasound examination, and it minimizes the chance of missed findings. Summary: The general principles for transabdominal, open intraoperative, and laparoscopic ultrasonography scanning are similar. One can gather considerable information using these modalities during a clinical examination, procedure, or operation. For success, it is critical to develop a standardized approach to scanning and use it every time. This facilitates familiarity when viewing images, making it easier for the novice to learn and gain experience. Using a systematic approach ensures that the experienced ultrasonographer obtains all the essential information needed at the time of surgery.

Efficacy of opioid spinal analgesia for postoperative pain management after pancreatoduodenectomy.

BACKGROUND: Efficacy of single-shot opioid spinal analgesia after pancreatoduodenectomy remains understudied and lacks comparison to standard continuous thoracic epidural analgesia (TEA). METHODS: Pancreatoduodenectomy patients who underwent TEA or opioid spinal for postoperative pain management from 2015 to 2020 were included in this observational cohort study. Primary outcome was patient-reported mean daily pain scores. Secondary outcomes included postoperative morphine milligram equivalents (MMEs) and length of stay (LOS). Multivariable linear regression models were constructed to compare risk-adjusted outcomes. RESULTS: 180 patients were included: 56 TEA and 124 opioid spinal. Compared to epidural patients, opioid spinal patients were more likely to be older (67.0 vs. 64.6, p=0.045), have greater BMI (26.5 vs. 24.4, p=0.02), and less likely to be smokers (19.4% vs. 41.1%, p=0.002). Opioid spinal, compared to TEA, was associated with lower intraoperative MMEs (0.25 vs. 22.7, p<0.001) and postoperative daily MMEs (7.9 vs. 10.3, p=0.03) on univariate analysis. However, after multivariable adjustment, there was no difference in average pain scores across the postoperative period (spinal vs. epidural: 4.18 vs. 4.14, p=0.93), daily MMEs (p=0.50), or LOS (p=0.23). DISCUSSION: There was no significant difference in postoperative pain scores, opioid use, or LOS between patients managed with TEA or opioid spinal after pancreatoduodenectomy.

Early Patient Discharge in Selected Patients is Not Associated With Higher Readmission After Major Abdominal Operations.

OBJECTIVE: Our objective was to examine the associations between early discharge and readmission after major abdominal operations. BACKGROUND: Advances in patient care resulted in earlier patient discharge after complex abdominal operations. Whether early discharge is associated with patient readmissions remains controversial. METHODS: Patients who had colorectal, liver, and pancreas operations abstracted in 2011-2017 American College of Surgeons National Surgical Quality Improvement Program Participant Use Data Files were included. Patient readmission was stratified by 6 operative groups. Patients who were discharged before median discharge date within each operative group were categorized as an early discharge. Analyses tested associations between early discharge and likelihood of 30-day postoperative unplanned readmission. RESULTS: A total of 364,609 patients with major abdominal operations were included. Individual patient groups and corresponding median day of discharge were: laparoscopic colectomy (n = 152,575; median = 4), open colectomy (n =137,462; median = 7), laparoscopic proctectomy (n = 12,238; median = 5), open proctectomy (n = 24,925; median = 6), major hepatectomy (n = 9,805; median = 6), pancreatoduodenectomy (n = 27,604; median = 8). Early discharge was not associated with an increase in proportion of readmissions in any operative group. Early discharge was associated with a decrease in average proportion of patient readmissions compared to patients discharged on median date in each of the operative groups: laparoscopic colectomy 6% versus 8%, open colectomy 11% versus 14%, laparoscopic proctectomy 13% versus 16%, open proctectomy 13% vs 17%, major hepatectomy 8% versus 12%, pancreatoduodenectomy 16% versus 20% (all P ≤ 0.02). Serious morbidity composite was significantly lower in patients who were discharged early than those who were not in each operative group (all P < 0.001). CONCLUSIONS: Early discharge in selected patients after major abdominal operations is associated with lower, and not higher, rate of 30-day unplanned readmission.

Surface Glycans Regulate Salmonella Infection-Dependent Directional Switch in Macrophage Galvanotaxis Independent of NanH.

Salmonella invades and disrupts gut epithelium integrity, creating an infection-generated electric field that can drive directional migration of macrophages, a process called galvanotaxis. Phagocytosis of bacteria reverses the direction of macrophage galvanotaxis, implicating a bioelectrical mechanism to initiate life-threatening disseminations. The force that drives direction reversal of macrophage galvanotaxis is not understood. One hypothesis is that Salmonella can alter the electrical properties of the macrophages by modifying host cell surface glycan composition, which is supported by the fact that cleavage of surface-exposed sialic acids with a bacterial neuraminidase severely impairs macrophage galvanotaxis, as well as phagocytosis. Here, we utilize N-glycan profiling by nanoLC-chip QTOF mass cytometry to characterize the bacterial neuraminidase-associated compositional shift of the macrophage glycocalyx, which revealed a decrease in sialylated and an increase in fucosylated and high mannose structures. The Salmonella nanH gene, encoding a putative neuraminidase, is required for invasion and internalization in a human colonic epithelial cell infection model. To determine whether NanH is required for the Salmonella infection-dependent direction reversal, we constructed and characterized a nanH deletion mutant and found that NanH is partially required for Salmonella infection in primary murine macrophages. However, compared to wild type Salmonella, infection with the nanH mutant only marginally reduced the cathode-oriented macrophage galvonotaxis, without canceling direction reversal. Together, these findings strongly suggest that while neuraminidase-mediated N-glycan modification impaired both macrophage phagocytosis and galvanotaxis, yet to be defined mechanisms other than NanH may play a more important role in bioelectrical control of macrophage trafficking, which potentially triggers dissemination.

Automated audio recording as a means of surveying tinamous (Tinamidae) in the Peruvian Amazon.

The use of machine learning technologies to process large quantities of remotely collected audio data is a powerful emerging research tool in ecology and conservation.We applied these methods to a field study of tinamou (Tinamidae) biology in Madre de Dios, Peru, a region expected to have high levels of interspecies competition and niche partitioning as a result of high tinamou alpha diversity. We used autonomous recording units to gather environmental audio over a period of several months at lowland rainforest sites in the Los Amigos Conservation Concession and developed a Convolutional Neural Network-based data processing pipeline to detect tinamou vocalizations in the dataset.The classified acoustic event data are comparable to similar metrics derived from an ongoing camera trapping survey at the same site, and it should be possible to combine the two datasets for future explorations of the target species' niche space parameters.Here, we provide an overview of the methodology used in the data collection and processing pipeline, offer general suggestions for processing large amounts of environmental audio data, and demonstrate how data collected in this manner can be used to answer questions about bird biology.

Interparticle Forces of a Native and Encapsulated Metal-Organic Framework and Their Effects on Colloidal Dispersion.

The colloidal properties of suspended metal-organic frameworks (MOFs) are critical for device fabrication and application. Herein, van der Waals attractive, electric double layer repulsive, and steric repulsive forces of a native and encapsulated MOF are quantified for the first time. The van der Waals attractive forces were investigated by conducting environmental ellipsometric porosimetry (EEP) and spectroscopic ellipsometry (SE) on submicron, optical-quality nanoparticle films. The repulsive forces were determined from colloid and material characterization measurements. These data were used to predict suspension properties via extended Derjaguin, Landau, Verwey, and Overbeek theory. The state of dispersion was quantified for comparison with theoretical predictions for nine solvents. The MOF encapsulated with a surface-selective modification showed superior suspension in hydrophobic solvents. These findings should expedite the formulation of MOF colloidal suspensions for future works.

A Potent Anti-Malarial Human Monoclonal Antibody Targets Circumsporozoite Protein Minor Repeats and Neutralizes Sporozoites in the Liver.

Discovering potent human monoclonal antibodies (mAbs) targeting the Plasmodium falciparum circumsporozoite protein (PfCSP) on sporozoites (SPZ) and elucidating their mechanisms of neutralization will facilitate translation for passive prophylaxis and aid next-generation vaccine development. Here, we isolated a neutralizing human mAb, L9 that preferentially bound NVDP minor repeats of PfCSP with high affinity while cross-reacting with NANP major repeats. L9 was more potent than six published neutralizing human PfCSP mAbs at mediating protection against mosquito bite challenge in mice. Isothermal titration calorimetry and multiphoton microscopy showed that L9 and the other most protective mAbs bound PfCSP with two binding events and mediated protection by killing SPZ in the liver and by preventing their egress from sinusoids and traversal of hepatocytes. This study defines the subdominant PfCSP minor repeats as neutralizing epitopes, identifies an in vitro biophysical correlate of SPZ neutralization, and demonstrates that the liver is an important site for antibodies to prevent malaria.

The impact of cirrhosis and MELD score on postoperative morbidity and mortality among patients selected for liver resection.

BACKGROUND: Independent associations between chronic liver disease, MELD, and postoperative outcomes among patients selected for liver resection have not been completely established. We hypothesized independent associations between MELD, cirrhosis, and postoperative mortality. METHODS: Patient-level data from the targeted hepatectomy module and ACS NSQIP PUF during 2014-2015 were merged. Multivariable regression models with interaction effect between MELD and liver texture (normal, congested/fatty, cirrhotic) tested the independent effects of covariates on mortality and morbidity. RESULTS: 3,530 patients were included, of whom 668 patients (19%) had cirrhosis. ACS NSQIP defined mortality (3.9%vs1.1%) and morbidity (23.5%vs15.8%) were higher in patients with cirrhosis (both p < 0.001). In multivariable models, cirrhosis (OR = 2.24; 95%CI:1.16-4.34, p = 0.016) and MELD (OR = 1.10; 95%CI:1.03-1.18, p = 0.007) were independently associated with mortality. MELD (OR = 1.04; 95%CI:1.002-1.08, p = 0.038) was associated with postoperative morbidity. CONCLUSIONS: Higher MELD and presence of cirrhosis have an independent negative effect on mortality after liver resection. MELD could be used to estimate postoperative risk in patients with and without cirrhosis.

Efficacy of Radiofrequency Ablation versus Transarterial Chemoembolization for Patients with Solitary Hepatocellular Carcinoma ≤3 cm.

Optimal treatment for small hepatocellular carcinoma (HCC) ≤ 3 cm remains controversial. Ablation and chemoembolization are considered for nonoperative candidates. This study compares survival among patients with solitary HCC ≤ 3 cm treated with radiofrequency ablation (RFA) and transarterial chemoembolization (TACE). Patients diagnosed with HCC ≤ 3 cm between 2005 and 2014 were included. Kaplan-Meier survival functions with log-rank tests were used to estimate recurrence-free survival and overall survival (OS) survival. Among 161 patients with solitary HCC ≤ 3 cm, 145 patients with mean age of 65.2 years (±9.2) and 95 per cent prevalence of cirrhosis had operative treatment or TACE, and/or RFA. From this cohort, 27 (19%) patients had TACE, 27 (19%) patients had RFA, and 15 (10%) patients had TACE/RFA. The patients treated with definitive TACE, RFA, or TACE/RFA had a similar 1-year recurrence-free survival (23% vs 27% vs 36%, respectively, P = 0.445) and similar 5-year OS (21% vs 24% vs 33%, respectively, P = 0.287). Thirty-five (24%) patients were bridged to transplantation with TACE and/or RFA. The 5-year OS was significantly improved in patients bridged to transplantation (P < 0.001). Survival does not differ between patients with solitary HCC ≤ 3 cm treated with TACE or RFA. Patients who were bridged to transplantation had significantly greater OS compared with patients who were not transplanted.

Water residence time (age) and flow path exert synchronous effects on annual characteristics of dissolved organic carbon in terrestrial runoff.

Catchment hydro-physical controls on the interannual variability of dissolved organic carbon (DOC) in terrestrial watershed runoff, important for water quality, ecosystem structure, and foodweb dynamics, are not well understood. To address this, we simulated water residence time ("age") and flow path of terrestrial runoff and analyzed their mediating effect on relationships between annual runoff volume, DOC concentration, and DOC age. We applied this analysis to a snow-influenced watershed in California's Sierra Nevada (USA) across a range of soil types, elevations (90-4210 m), and years (1950-1999). Simulated increases in annual runoff volume were accompanied by younger ages (r2 = 0.53-0.63) of DOC in quickflow, comprised of surface runoff and lateral flow through soil. Increases in annual runoff volume were also accompanied by gentler relationships between intra-annual (weekly) values of DOC concentration and runoff volume, regression-slopes of which followed a power-law relationship to annual runoff (r2 = 0.12-0.92) for approximately 70% of the watershed. Simulations including dynamics of water age and soil temperature produced annual ages of quickflow DOC ranging from 1 to 70 days over all soil types and water years. Similarity of this range to an observed, 1-69 day range in half-lives of relatively labile DOC in previous studies suggests substantial interannual and spatial variability in the biodegradability of DOC in terrestrial runoff. Simulations excluding dynamics of water age and soil temperature predicted order-of-magnitude less interannual variability in age of quickflow DOC, demonstrating the important effect of interannual variability in soil-water interaction times. These findings suggest that the distribution of DOC bioprocessing along transitions between terrestrial and aquatic systems may be strongly influenced by year-to-year variability in age of water.

Disentangling the genetic effects of refugial isolation and range expansion in a trans-continentally distributed species.

In wide-ranging taxa with historically dynamic ranges, past allopatric isolation and range expansion can both influence the current structure of genetic diversity. Considering alternate historical scenarios involving expansion from either a single refugium or from multiple refugia can be useful in differentiating the effects of isolation and expansion. Here, we examined patterns of genetic variability in the trans-continentally distributed painted turtle (Chrysemys picta). We utilized an existing phylogeographic dataset for the mitochondrial control region and generated additional data from nine populations for the mitochondrial control region (n = 302) and for eleven nuclear microsatellite loci (n = 247). We created a present-day ecological niche model (ENM) for C. picta and hindcast this model to three reconstructions of historical climate to define three potential scenarios with one, two, or three refugia. Finally, we employed spatially-explicit coalescent simulations and an approximate Bayesian computation (ABC) framework to test which scenario best fit the observed genetic data. Simulations indicated that phylogeographic and multilocus population-level sampling both could differentiate among refugial scenarios, although inferences made using mitochondrial data were less accurate when a longer coalescence time was assumed. Furthermore, all empirical genetic datasets were most consistent with expansion from a single refugium based on ABC. Our results indicate a stronger role for post-glacial range expansion, rather than isolation in allopatric refugia followed by range expansion, in structuring diversity in this species. To distinguish among complex historical scenarios, we recommend explicitly modeling the effects of range expansion and evaluating alternate refugial scenarios for wide-ranging taxa.

Mortality after pancreaticoduodenectomy: assessing early and late causes of patient death.

BACKGROUND: Safety of pancreaticoduodenectomy has improved significantly in the past 3 decades. Current inpatient and 30-d mortality rates are low. However, incidence and causes of 90-d and 1-y mortality are poorly defined and largely unexplored. METHODS: All patients who had pancreaticoduodenectomy between 2007 and 2016 were included in this single institution, retrospective cohort study. Distributions of pancreaticoduodenectomy-specific morbidity and cause-specific mortality were compared between early (within 90 d) and late (91-365 d) postoperative recovery periods. RESULTS: A total of 551 pancreaticoduodenectomies were performed during the study period. Of these, 6 (1.1%), 20 (3.6%), and 91 (16.5%) patients died within 30, 90, and 365 d after pancreaticoduodenectomy, respectively. Causes of early and late mortality varied significantly (all P ≤ 0.032). The most common cause of death within 90 d was due to multisystem organ failure from sepsis or aspiration in 9 (45%) patients, followed by post-pancreatectomy hemorrhage in 5 (25%) patients, and cardiopulmonary arrest from myocardial infarction or pulmonary embolus in 3 (15%) patients. In contrast, recurrent cancer was the most common cause of death in 46 (65%) patients during the late postoperative period between 91 and 365 d. Mortality from failure to thrive and debility was similar between early and late postoperative periods (15% versus 19.7%, P = 0.76). CONCLUSIONS: Most quality improvement initiatives in patients selected for pancreaticoduodenectomy have focused on reduction of technical complications and improvement of early postoperative mortality. Further reduction in postoperative mortality after pancreaticoduodenectomy can be achieved by improving patient selection, mitigating postoperative malnutrition, and optimizing preoperative cancer staging and management strategies.

Pancreatic duct size and gland texture are associated with pancreatic fistula after pancreaticoduodenectomy but not after distal pancreatectomy.

BACKGROUND: Pancreatic fistula remains a morbid complication after pancreatectomy. Since the proposed mechanism of pancreatic fistula is different between pancreaticoduodenectomy and distal pancreatectomy, we hypothesized that pancreatic gland texture and duct size are not associated with pancreatic fistula after distal pancreatectomy. METHODS: All patients ≥18 years in the 2014-15 American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) targeted pancreatectomy dataset were linked with the ACS NSQIP Public Use File (PUF). Pancreatic duct size (<3 mm, 3-6 mm, >6 mm) and pancreatic gland texture (hard, intermediate, soft) were categorized. Separate multivariable analyses were performed to evaluate associations between pancreatic duct size and gland texture after pancreaticoduodenectomy and distal pancreatectomy. RESULTS: A total of 9366 patients underwent pancreaticoduodenectomy or distal pancreatectomy during the study period. Proportion of pancreatic fistula was similar after distal pancreatectomy (606 of 3132, 19.4%) and pancreaticoduodenectomy (1163 of 6335, 18.4%, p = 0.245). Both pancreatic gland texture and duct size were significantly associated with pancreatic fistula after pancreaticoduodenectomy (p<0.001). However, there was no association between pancreatic fistula and gland texture or duct size (all p≥0.169) after distal pancreatectomy. Operative approach (minimally invasive versus open) was not associated with pancreatic fistula after distal pancreatectomy (p = 0.626). Patients with pancreatic fistula after distal pancreatectomy had increased rate of postoperative complications including longer length of stay, higher rates of readmission and reoperation compared to patients who did not have a pancreatic fistula (all p<0.001). CONCLUSIONS: Unlike among patients who had pancreaticoduodenectomy, pancreatic gland texture and duct size are not associated with development of pancreatic fistula following distal pancreatectomy. Other clinical factors should be considered in this patient population.

Molecular signatures of host specificity linked to habitat specialization in Exaiptasia sea anemones.

Rising ocean temperatures associated with global climate change induce breakdown of the symbiosis between coelenterates and photosynthetic microalgae of the genus Symbiodinium. Association with more thermotolerant partners could contribute to resilience, but the genetic mechanisms controlling specificity of hosts for particular Symbiodinium types are poorly known. Here, we characterize wild populations of a sea anemone laboratory model system for anthozoan symbiosis, from contrasting environments in Caribbean Panama. Patterns of anemone abundance and symbiont diversity were consistent with specialization of holobionts for particular habitats, with Exaiptasia pallida/S. minutum (ITS2 type B1) abundant on vertical substrate in thermally stable, shaded environments but E. brasiliensis/Symbiodinium sp. (ITS2 clade A) more common in shallow areas subject to high temperature and irradiance. Population genomic sequencing revealed a novel E. pallida population from the Bocas del Toro Archipelago that only harbors S. minutum. Loci most strongly associated with divergence of the Bocas-specific population were enriched in genes with putative roles in cnidarian symbiosis, including activators of the complement pathway of the innate immune system, thrombospondin-type-1 repeat domain proteins, and coordinators of endocytic recycling. Our findings underscore the importance of unmasking cryptic diversity in natural populations and the role of long-term evolutionary history in mediating interactions with Symbiodinium.

An age-dependent vocal tract model for males and females based on anatomic measurements.

The purpose of this study was to take a first step toward constructing a developmental and sex-specific version of a parametric vocal tract area function model representative of male and female vocal tracts ranging in age from infancy to 12 yrs, as well as adults. Anatomic measurements collected from a large imaging database of male and female children and adults provided the dataset from which length warping and cross-dimension scaling functions were derived, and applied to the adult-based vocal tract model to project it backward along an age continuum. The resulting model was assessed qualitatively by projecting hypothetical vocal tract shapes onto midsagittal images from the cohort of children, and quantitatively by comparison of formant frequencies produced by the model to those reported in the literature. An additional validation of modeled vocal tract shapes was made possible by comparison to cross-sectional area measurements obtained for children and adults using acoustic pharyngometry. This initial attempt to generate a sex-specific developmental vocal tract model paves a path to study the relation of vocal tract dimensions to documented prepubertal acoustic differences.