Dollars and Sense: The Business of Pediatric Surgery.

INTRODUCTION: This study evaluated North American pediatric surgeons' opinions and knowledge of business and economics in medicine and their perceptions of trends in their healthcare delivery environment. METHODS: We conducted an elective online survey of 1119 American Pediatric Surgical Association members. Over 8 mo, we iteratively developed the survey focused on four areas: opinion, knowledge, current practice environment, and trends in practice environment over the past 5 y. RESULTS: We received 227 (20.3%) complete surveys from pediatric surgeons. One hundred ninety four (85.5%) perceive healthcare as a business and most (85.9%) believe healthcare decisions may affect patients' out-of-pocket expenses. More than half (51.1%) of surgeons believe it has become more challenging to perform emergent cases and most believe staff quality has decreased for elective (56.4%) and emergent (63.0%) cases over the past 5 y. CONCLUSIONS: Pediatric surgeons recognize that medicine is a business and have concerns regarding the decreasing quality of operating room staff and the increasing difficulty providing surgical care over the last 5 y.

Disparities in care of pediatric, adolescent, and young adult patients with solid tumors: A systematic review.

BACKGROUND: Numerous studies have demonstrated a variety of social inequalities within pediatric and young adult patients with solid tumors. This systematic review examines and consolidates the existing literature regarding disparities in pediatric and young adult solid tumor oncology. PROCEDURE: A MeSH search was performed on the following databases: MEDLINE, PubMed, OvidSP Cochrane, Central, Embase, Cinhal, and Scopus. The systematic review was performed using Rayyan QCRI. RESULTS: Total 387 articles were found on the initial search, and 34 articles were included in final review. Twenty-seven studies addressed racial and ethnic disparities; 23 addressed socioeconomic disparities. Patients with Hispanic ethnicity, Black race, and lower socioeconomic status were more likely to present at later stages, have differences in treatments and higher mortality rates. CONCLUSION: This qualitative systematic review identified both racial and socioeconomic disparities in pediatric cancer patients across a variety of solid tumor types. Patients with Hispanic ethnicity, Black race, and lower socioeconomic status are associated with disparities in stage at presentation, treatment, and outcome. Characterization of existing disparities provides the evidence necessary to support changes at a systemic level.

Genetic Architecture of Maize Rind Strength Revealed by the Analysis of Divergently Selected Populations.

The strength of the stalk rind, measured as rind penetrometer resistance (RPR), is an important contributor to stalk lodging resistance. To enhance the genetic architecture of RPR, we combined selection mapping on populations developed by 15 cycles of divergent selection for high and low RPR with time-course transcriptomic and metabolic analyses of the stalks. Divergent selection significantly altered allele frequencies of 3,656 and 3,412 single- nucleotide polymorphisms (SNPs) in the high and low RPR populations, respectively. Surprisingly, only 110 (1.56%) SNPs under selection were common in both populations, while the majority (98.4%) were unique to each population. This result indicated that high and low RPR phenotypes are produced by biologically distinct mechanisms. Remarkably, regions harboring lignin and polysaccharide genes were preferentially selected in high and low RPR populations, respectively. The preferential selection was manifested as higher lignification and increased saccharification of the high and low RPR stalks, respectively. The evolution of distinct gene classes according to the direction of selection was unexpected in the context of parallel evolution and demonstrated that selection for a trait, albeit in different directions, does not necessarily act on the same genes. Tricin, a grass-specific monolignol that initiates the incorporation of lignin in the cell walls, emerged as a key determinant of RPR. Integration of selection mapping and transcriptomic analyses with published genetic studies of RPR identified several candidate genes including ZmMYB31, ZmNAC25, ZmMADS1, ZmEXPA2, ZmIAA41 and hk5. These findings provide a foundation for an enhanced understanding of RPR and the improvement of stalk lodging resistance.

On measuring the bending strength of septate grass stems.

UNLABELLED: • PREMISE OF THE STUDY: Reliable testing methodologies are a fundamental tenet of scientific research. However, very little information is found in the literature explaining how to accurately measure the structural bending strength of plant stems. It was hypothesized that the most commonly employed loading configuration used in bending experiments (placement of loading anvil at an internodal region of the stem or stalk) may significantly alter test results and introduce errors in bending strength measurements of plant stems.• METHODS: Four types of mechanical tests were performed on bamboo (Phyllostachys aurea), giant reed (Arundo donax), and maize (Zea mays) to investigate how different loading configurations employed during three-point bending experiments affect test results of septate grass stems and to develop a testing protocol that provides reliable measures of stalk bending strength.• RESULTS: RESULTS confirmed the hypothesis that internodal-loaded three-point bending test can produce erroneous bending strength measurements. This testing methodology causes plant stems to break prematurely and produces failure types and patterns incongruent with stalks that broke in their natural (in situ) environment. In contrast, a modified test configuration produces natural failure patterns and more accurate measurements of bending strength.• CONCLUSION: Reliable measurements of stalk bending strength can be obtained by maximizing the span length of bending tests and placing the loading anvil at stronger and denser nodal tissues. These results are relevant to ecological and evolutionary plant biomechanics studies as well as agronomic breeding studies focused on measuring plant phenotypes such as stalk lodging strength, or on improving bending strength of septate plant stems.

Cost and safety of pediatric intensive care physician-placed broviac catheters.

OBJECTIVE: To compare the cost and safety of placement of Broviac catheters in children by pediatric intensivists in a sedation suite versus placement by pediatric surgeons in the operating room. DESIGN: Single-center retrospective analysis. SETTING: Pediatric sedation suite and operating rooms in a tertiary care children's hospital. PATIENTS: All pediatric patients with Broviac catheters placed (n = 253) at this institution over a 3-year period from 2007 to 2009. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We reviewed the charts of all pediatric patients with Broviac catheters placed, either by intensivists or surgeons, and compared cost and outcomes. Procedure safety was assessed and categorized into immediate, short-term (within 2 wk of procedure), and long-term outcomes. Anesthetic safety and billing data for the procedure were also collected. Among similar patient populations, immediate complications, such as pneumothorax, procedure failure (p > 0.999), and anesthetic complications (p = 0.60), were not significantly different. Short-term outcomes, including infection (p = 0.27) and catheter malfunction (p > 0.999), were not different. Long-term outcomes, including mean indwelling catheter days (p = 0.60) and removal due to catheter infection (p = 0.09), were not different between the groups. Overall cost of the procedure was significantly different: $7,031 (± $784) when performed by surgeons and $3,565 (± $311) when performed by intensivists (p < 0.001). CONCLUSIONS: Pediatric critical care physicians can place Broviac catheters as safely as pediatric surgeons and at a lower cost in a defined patient population.

The effect of testing rate on biomechanical measurements related to stalk lodging.

BACKGROUND: Stalk lodging (the premature breaking of plant stalks or stems prior to harvest) is a persistent agricultural problem that causes billions of dollars in lost yield every year. Three-point bending tests, and rind puncture tests are common biomechanical measurements utilized to investigate crops susceptibility to lodging. However, the effect of testing rate on these biomechanical measurements is not well understood. In general, biological specimens (including plant stems) are well known to exhibit viscoelastic mechanical properties, thus their mechanical response is dependent upon the rate at which they are deflected. However, there is very little information in the literature regarding the effect of testing rate (aka displacement rate) on flexural stiffness, bending strength and rind puncture measurements of plant stems. RESULTS: Fully mature and senesced maize stems and wheat stems were tested in three-point bending at various rates. Maize stems were also subjected to rind penetration tests at various rates. Testing rate had a small effect on flexural stiffness and bending strength calculations obtained from three-point bending tests. Rind puncture measurements exhibited strong rate dependent effects. As puncture rate increased, puncture force decreased. This was unexpected as viscoelastic materials typically show an increase in resistive force when rate is increased. CONCLUSIONS: Testing rate influenced three-point bending test results and rind puncture measurements of fully mature and dry plant stems. In green stems these effects are expected to be even larger. When conducting biomechanical tests of plant stems it is important to utilize consistent span lengths and displacement rates within a study. Ideally samples should be tested at a rate similar to what they would experience in-vivo.

Diaphragmatic pacing for respiratory failure in children.

Diaphragm pacing is a ventilation strategy in respiratory failure. Most of the literature on pacing involves adults with common indications being spinal cord injury and amyotrophic lateral sclerosis (ALS). Previous reports in pediatric patients consist of case reports or small series; most describe direct phrenic nerve stimulation for central hypoventilation syndrome. This differs from adult reports that focus most commonly on spinal cord injuries and the rehabilitative nature of diaphragm pacing. This review describes the current state of diaphragm pacing in pediatric patients. Indications, current available technologies, surgical techniques, advantages, and pitfalls/problems are discussed.

Virtual reality applications in pediatric surgery.

Virtual reality modeling (VRM) is a 3-dimensional (3D) simulation. It is a powerful tool and has multiple uses and applications in pediatric surgery. Patient-specific 2-dimensional imaging can be used to generate a virtual reality model, which can improve anatomical perception and understanding, and can aid in preoperative planning for complex operations. VRM can also be used for realistic training and simulation. It has also proven effective in distraction for pediatric patients experiencing pain and/or anxiety. We detail the technical requirements and process required for VRM generation, the applications, and future directions.

Virtual Reality for Preoperative Surgical Planning in Complex Pediatric Oncology.

Background: Virtual reality modeling (VRM) is a 3-dimensional simulation created from patient-specific 2-dimensional (2D) imaging. VRM creates a more accurate representation of the patient anatomy and can improve anatomical perception. We surveyed surgeons on their operative plan in complex pediatric oncology cases based on review of 2D imaging and subsequently after review of VRM. We hypothesized that the confidence level would increase with the use of virtual reality and that VRM may change the operative plan. Methods: Patients were selected and enrolled based on age (<18) and oncological diagnosis. VRM was created based on the 2D imaging. Surgeons identified surgical plans based on 2D imaging and again after VRM. A blinded surgeon not involved with the case also gave opinions on surgical plans after viewing both the 2D and the VRM imaging. These assessments were compared with the actual operation. Results: A total of 12 patients were enrolled. Diagnoses included six neuroblastomas, two Wilms tumors, one Ewing's sarcoma, one pseudopapillary tumor of the pancreas, one rhabdomyosarcoma, and one mediastinal germ cell tumor. VRM increased the operating surgeon's confidence 63% of the time. The operative plan changed 8.3% of the time after VRM. Conclusion: VRM is useful to help clarify operative plans for more complex pediatric cases.

Biomechanical phenotyping pipeline for stalk lodging resistance in maize.

Stalk lodging (structural failure crops prior to harvest) significantly reduces annual yields of vital grain crops. The lack of standardized, high throughput phenotyping methods capable of quantifying biomechanical plant traits prevents comprehensive understanding of the genetic architecture of stalk lodging resistance. A phenotyping pipeline developed to enable higher throughput biomechanical measurements of plant traits related to stalk lodging is presented. The methods were developed using principles from the fields of engineering mechanics and metrology and they enable retention of plant-specific data instead of averaging data across plots as is typical in most phenotyping studies. This pipeline was specifically designed to be implemented in large experimental studies and has been used to phenotype over 40,000 maize stalks. The pipeline includes both lab- and field-based phenotyping methodologies and enables the collection of metadata. Best practices learned by implementing this pipeline over the past three years are presented. The specific instruments (including model numbers and manufacturers) that work well for these methods are presented, however comparable instruments may be used in conjunction with these methods as seen fit.•Efficient methods to measure biomechanical traits and record metadata related to stalk lodging.•Can be used in studies with large sample sizes (i.e., > 1,000).

The semi-automated development of plant cell wall finite element models.

This study presents a methodology for a high-throughput digitization and quantification process of plant cell walls characterization, including the automated development of two-dimensional finite element models. Custom algorithms based on machine learning can also analyze the cellular microstructure for phenotypes such as cell size, cell wall curvature, and cell wall orientation. To demonstrate the utility of these models, a series of compound microscope images of both herbaceous and woody representatives were observed and processed. In addition, parametric analyses were performed on the resulting finite element models. Sensitivity analyses of the structural stiffness of the resulting tissue based on the cell wall elastic modulus and the cell wall thickness; demonstrated that the cell wall thickness has a three-fold larger impact of tissue stiffness than cell wall elastic modulus.

High throughput phenotyping of cross-sectional morphology to assess stalk lodging resistance.

BACKGROUND: Stalk lodging (mechanical failure of plant stems during windstorms) leads to global yield losses in cereal crops estimated to range from 5% to 25% annually. The cross-sectional morphology of plant stalks is a key determinant of stalk lodging resistance. However, previously developed techniques for quantifying cross-sectional morphology of plant stalks are relatively low-throughput, expensive and often require specialized equipment and expertise. There is need for a simple and cost-effective technique to quantify plant traits related to stalk lodging resistance in a high-throughput manner. RESULTS: A new phenotyping methodology was developed and applied to a range of plant samples including, maize (Zea mays), sorghum (Sorghum bicolor), wheat (Triticum aestivum), poison hemlock (Conium maculatum), and Arabidopsis (Arabis thaliana). The major diameter, minor diameter, rind thickness and number of vascular bundles were quantified for each of these plant types. Linear correlation analyses demonstrated strong agreement between the newly developed method and more time-consuming manual techniques (R2 > 0.9). In addition, the new method was used to generate several specimen-specific finite element models of plant stalks. All the models compiled without issue and were successfully imported into finite element software for analysis. All the models demonstrated reasonable and stable solutions when subjected to realistic applied loads. CONCLUSIONS: A rapid, low-cost, and user-friendly phenotyping methodology was developed to quantify two-dimensional plant cross-sections. The methodology offers reduced sample preparation time and cost as compared to previously developed techniques. The new methodology employs a stereoscope and a semi-automated image processing algorithm. The algorithm can be used to produce specimen-specific, dimensionally accurate computational models (including finite element models) of plant stalks.

Cross-sectional geometry predicts failure location in maize stalks.

BACKGROUND: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Stalk lodging occurs when high winds induce bending moments in the stalk which exceed the bending strength of the plant. Previous biomechanical models of plant stalks have investigated the effect of cross-sectional morphology on stalk lodging resistance (e.g., diameter and rind thickness). However, it is unclear if the location of stalk failure along the length of stem is determined by morphological or compositional factors. It is also unclear if the crops are structurally optimized, i.e., if the plants allocate structural biomass to create uniform and minimal bending stresses in the plant tissues. The purpose of this paper is twofold: (1) to investigate the relationship between bending stress and failure location of maize stalks, and (2) to investigate the potential of phenotyping for internode-level bending stresses to assess lodging resistance. RESULTS: 868 maize specimens representing 16 maize hybrids were successfully tested in bending to failure. Internode morphology was measured, and bending stresses were calculated. It was found that bending stress is highly and positively associated with failure location. A user-friendly computational tool is presented to help plant breeders in phenotyping for internode-level bending stress. Phenotyping for internode-level bending stresses could potentially be used to breed for more biomechanically optimal stalks that are resistant to stalk lodging. CONCLUSIONS: Internode-level bending stress plays a potentially critical role in the structural integrity of plant stems. Equations and tools provided herein enable researchers to account for this phenotype, which has the potential to increase the bending strength of plants without increasing overall structural biomass.

The Overlooked Biomechanical Role of the Clasping Leaf Sheath in Wheat Stalk Lodging.

The biomechanical role of the clasping leaf sheath in stalk lodging events has been historically understudied. Results from this study indicate that in some instances the leaf sheath plays an even larger role in reinforcing wheat against stalk lodging than the stem itself. Interestingly, it appears the leaf sheath does not resist bending loads by merely adding more material to the stalk (i.e., increasing the effective diameter). The radial preload of the leaf sheath on the stem, the friction between the sheath and the stem and several other complex biomechanical factors may contribute to increasing the stalk bending strength and stalk flexural rigidity of wheat. Results demonstrated that removal of the leaf sheath induces alternate failure patterns in wheat stalks. In summary the biomechanical role of the leaf sheath is complex and has yet to be fully elucidated. Many future studies are needed to develop high throughput phenotyping methodologies and to determine the genetic underpinnings of the clasping leaf sheath and its relation to stalk lodging resistance. Research in this area is expected to improve the lodging resistance of wheat.

The Crop Clamp - A non-destructive electromechanical pinch test to evaluate stalk lodging resistance.

Given the ever-increasing world population, maize plays a pivotal role in global food security. A major obstacle facing farmers is stalk lodging (the breakage of the stalk before harvest), which leads to substantial losses in annual yields. Weather, disease, and pest damage are major contributors to stalk lodging. Traditionally, evaluating a stalk's tendency to lodge was achieved with a 'pinch' test: pinching the stalk by hand to estimate its transverse stiffness. This test is inherently qualitative, and results vary from person to person. To combat these problems, a portable, battery-operated, non-destructive device for precisely measuring the transverse stiffness of maize stalks, known as the Crop Clamp, has been developed. The device is capable of recording over 100 measurements per hour and has been validated against laboratory tests.

A novel rind puncture technique to measure rind thickness and diameter in plant stalks.

BACKGROUND: Measurements of rind and culm thickness and stem radius/diameter are important to biomechanical, ecological and physiological plant studies. However, many methods of measuring rind thickness and diameter are labor intensive and induce plant fatality. A novel rind puncture methodology for obtaining measurements of rind thickness and diameter has been developed. The suitability of the new method for implementation in plant studies is presented. RESULTS: The novel rind puncture technique was used to obtain measurements of rind thickness and diameter for samples of Poison Hemlock (Conium maculatum). The rind puncture measurements were strongly correlated with caliper measurements (R2 > 0.97) and photographic image analysis measurements (R2 > 0.84). The capacity for high throughput measurements using the rind puncture technique was determined to exceed that of caliper measurements and image analysis techniques. CONCLUSIONS: The rind puncture technique shows promise as a high throughput method for determining rind thickness and diameter as it is cost effective and non-lethal. The authors are currently working to develop a custom handheld apparatus to allow the novel rind puncture method to be used in field work. High throughput field-based measurements of rind thickness and diameter are needed to help address the problem of stalk lodging (failure of grain crops to remain upright until harvest).

The effect of probe geometry on rind puncture resistance testing of maize stalks.

BACKGROUND: Stalk lodging (breaking of plant stems prior to harvest) is a major impediment to increasing agricultural yields of grain crops. Rind puncture resistance is commonly used to predict the lodging resistance of several crop species. However, there exist no standard operating procedures or suggested protocols for conducting rind penetration experiments. In addition, experimental details of rind penetration tests such as the shape and size of the penetrating probe are rarely reported in the literature. This has prevented meta-analysis of results and has likewise prevented key findings of past studies from being replicated. As a first step towards establishing an agreed upon measurement standard for rind puncture resistance this study investigates the effect of the puncturing probe's geometry on test results. RESULTS: Results demonstrate that probe geometry has a significant impact on test results. In particular, results showed that a 2 mm diameter chamfered probe produced stronger correlations with stalk bending strength than a 1.5 mm diameter pointed probe. The chamfered probe was also more strongly correlated with geometric features of the stalk that are known to influence stalk lodging resistance (e.g., rind thickness, diameter and section modulus). In addition, several alternative rind penetration metrics were investigated, and some were found to be superior to the most common rind penetration metric of maximum load. CONCLUSIONS: There is a need in the agricultural and plant science community to create agreed-upon operating procedures and testing standards related to mechanical traits of plant stems. In particular, a standardized probe geometry and insertion rate for rind penetration studies are needed to enable greater interoperability and meta-analysis of results. Probe shape and size should be reported in any study conducting rind penetration tests as these factors significantly impact test results.

Diverse maize hybrids are structurally inefficient at resisting wind induced bending forces that cause stalk lodging.

BACKGROUND: Stalk lodging (breaking of agricultural plant stalks prior to harvest) results in millions of dollars in lost revenue each year. Despite a growing body of literature on the topic of stalk lodging, the structural efficiency of maize stalks has not been investigated previously. In this study, we investigate the morphology of mature maize stalks to determine if rind tissues, which are the major load bearing component of corn stalks, are efficiently organized to withstand wind induced bending stresses that cause stalk lodging. RESULTS: 945 fully mature, dried commercial hybrid maize stem specimens (48 hybrids, ~ 2 replicates, ~ 10 samples per plot) were subjected to: (1) three-point-bending tests to measure their bending strength and (2) rind penetration tests to measure the cross-sectional morphology at each internode. The data were analyzed through an engineering optimization algorithm to determine the structural efficiency of the specimens. CONCLUSIONS: Hybrids with higher average bending strengths were found to allocate rind tissue more efficiently than weaker hybrids. However, even strong hybrids were structurally suboptimal. There remains significant room for improving the structural efficiency of maize stalks. Results also indicated that stalks are morphologically organized to resist wind loading that occurs primarily above the ear. Results are applicable to selective breeding and crop management studies seeking to reduce stalk lodging rates.

Field-based mechanical phenotyping of cereal crops to assess lodging resistance.

Plant mechanical failure, also known as lodging, is the cause of significant and unpredictable yield losses in cereal crops. Lodging occurs in two distinct failure modes-stalk lodging and root lodging. Despite the prevalence and detrimental impact of lodging on crop yields, there is little consensus on how to phenotype plants in the field for lodging resistance and thus breed for mechanically resilient plants. This review provides an overview of field-based mechanical testing approaches to assess stalk and root lodging resistance. These approaches are placed in the context of future perspectives. Best practices and recommendations for acquiring field-based mechanical phenotypes of plants are also presented.

Integrated Puncture Score: force-displacement weighted rind penetration tests improve stalk lodging resistance estimations in maize.

BACKGROUND: Stalk lodging (breaking of agricultural plant stalks prior to harvest) is a multi-billion dollar a year problem. Rind penetration resistance tests have been used by plant scientists and breeders to estimate the stalk lodging resistance of maize for nearly a hundred years. However, the rind puncture method has two key limitations: (1) the predictive power of the test decreases significantly when measuring elite or pre-commercial hybrids, and (2) using rind penetration measurements as a breeding metric does not necessarily create stronger stalks. In this study, we present a new rind penetration method called the Integrated Puncture Score, which uses a modified rind penetration testing protocol and a physics-based model to provide a robust measure of stalk lodging resistance. RESULTS: Two datasets, one with a diverse array of maize hybrids and one with only elite hybrids, were evaluated by comparing traditional rind penetration testing and the Integrated Puncture Score method to measurements of stalk bending strength. When evaluating the diverse set of hybrids, both methods were good predictors of stalk bending strength (R2 values of 0.67). However, when evaluating elite hybrids, the Integrated Puncture Score had an R2 value of 0.74 whereas the traditional method had an R2 value of 0.48. Additionally, the Integrated Puncture Score was able to differentiate between the strongest and weakest hybrids in the elite hybrid data set whereas the traditional rind penetration method was not. Additional experiments revealed strong evidence in favor of the data aggregation steps utilized to compute the Integrated Puncture Score. CONCLUSIONS: This study presents a new method for evaluating rind penetration resistance that highly correlates with stalk bending strength and can possibly be used as a breeding index for assessing stalk lodging resistance. This research lays the foundation required to develop a field-based high-throughput phenotyping device for stalk lodging resistance.