Optimal Choice Research Articles

A Novel Noise-Aware Classical Optimizer for Variational Quantum Algorithms

A key component of variational quantum algorithms (VQAs) is the choice of classical optimizer employed to update the parameterization of an ansatz. It is well recognized that quantum algorithms will, for the foreseeable future, necessarily be run on noisy devices with limited fidelities. Thus, the evaluation of an objective function (e.g., the guiding function in the quantum approximate optimization algorithm (QAOA) or the expectation of the electronic Hamiltonian in variational quantum eigensolver (VQE)) required by a classical optimizer is subject not only to stochastic error from estimating an expected value but also to error resulting from intermittent hardware noise. Model-based derivative-free optimization methods have emerged as popular choices of a classical optimizer in the noisy VQA setting, based on empirical studies. However, these optimization methods were not explicitly designed with the consideration of noise. In this work we adapt recent developments from the “noise-aware numerical optimization” literature to these commonly used derivative-free model-based methods. We introduce the key defining characteristics of these novel noise-aware derivative-free model-based methods that separate them from standard model-based methods. We study an implementation of such noise-aware derivative-free model-based methods and compare its performance on demonstrative VQA simulations to classical solvers packaged in scikit-quant. History: Accepted by Giacomo Nannicini, Area Editor for Quantum Computing and Operations Research. Accepted for Special Issue. Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers and the Office of Advanced Scientific Computing Research, Accelerated Research for Quantum Computing program under contract number DE-AC02-06CH11357. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information ( https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2023.0177 ) as well as from the IJOC GitHub software repository ( https://github.com/INFORMSJoC/2023.0177 ). The complete IJOC Software and Data Repository is available at https://informsjoc.github.io/ .

Robustness meets co-jumps: optimal consumption and portfolio choice with derivatives

In this paper, we study a robust, dynamic, continuous-time optimal consumption and portfolio allocation problem for investors with recursive preferences who have access to both stock and derivatives markets. We assume the stock price process follows a stochastic volatility model, with instantaneous precision as the unique state variable, allowing for discontinuities in all the dynamics. We obtain a closed-form approximate solution up to a system of ODEs to the optimization problem for a non-unitary value of the elasticity of intertemporal substitution of consumption, being able to derive an exact solution as a particular case. Our theoretical findings show that the optimal policies are remarkably affected by the ambiguity-aversion parameters to diffusive and jump risks. A detailed numerical analysis confirms the effectiveness of our theoretical results on real data. Finally, we prove that investors who do not believe in ambiguity may suffer considerable wealth losses.

Machine learning and analytic hierarchy process integration for selecting a sustainable tractor.

Selecting the appropriate tractor for small-scale farms is a complex process due to the multitude of technical, environmental, and economic criteria that must be evaluated. This study addresses this challenge by integrating the Analytic Hierarchy Process (AHP) with machine learning (ML) to reduce the number of criteria and simplify the decision-making process. The research aims to determine the most relevant criteria aligned with sustainable development goals for selecting the right tractor, focusing on small farms in the Egyptian Delta. Four tractors, with horsepower ranging from 55 to 95, were evaluated based on inputs from forty-two governmental service providers in the study area. Initially, nine criteria were identified, encompassing key technical, environmental, and economic factors. These criteria were reduced to three-price, power, and maintenance costs by weights 0.142, 0.334, and 0.525, respectively-using Hierarchical Agglomerative Clustering with Euclidean distance. This reduction streamlined the selection process, making it more practical for farmers. Results show that the second tractor (T2), with a priority score of 0.326 and a normalized value of 33.4%, emerged as the optimal choice for small-scale farmers, outperforming the first tractor (T1) (28.7%) and third tractor (T3) (21%). Integrating AHP and ML simplifies tractor selection, ensuring sustainability, cost-efficiency, and operational effectiveness.

A New Ultra-Compact Communications System across Air-Sea Water Based on ELF Magnetic Mechanical Antenna

Abstract In this paper, a long-range trans-air-seawater medium communication system is proposed based on a small extremely low-frequency (ELF) mechanical antenna. We analyze the propagation characteristics of ELF electromagnetic waves in seawater and determine the paths of ELF electromagnetic waves propagating across domains. Equivalent models of various mechanical antennas are analyzed based on their operating principles. Based on the equivalent model, the transmission principle of mechanical antenna in transmitting across air-sea medium is analyzed, and finally the mechanical antenna with permanent magnet working horizontally is identified as the optimal choice. The above results are also verified by simulation. Experimental and simulation results verify the good performance of a horizontally operating permanent magnet mechanical antenna in transmitting across air-sea medium. The ELF-band transmission communication across air-sea medium based on binary code modulation is realized, and the farthest transmission distance can reach 200m in the experiment. Based on this system, transmission in air was also tested up to a distance of 1.5km. The ELF transmission across air-sea medium based on a permanent magnet mechanical antenna can greatly facilitate cross-domain teleportation and ocean exploration.

What Type of Self-Assessment Is Best for Your Educational Activity? A Review of Pre-Post, Now-Then, and Post-Only Designs.

In medical education, learner self-assessments are standard methods used to evaluate the impact of curricula and workshops. Due to the subjective nature of self-assessment, these measures are prone to known biases including framing, recall, social desirability, and response-shift bias. These biases can contribute to floor and ceiling effects of measurement, which can lead to false conclusions about whether the intended learning objectives were achieved. Ideal assessments of skills-based educational activities would include standardized tests and structured observations of learners demonstrating skill use before and after the educational intervention. However, educators often lack the necessary resources, time, and expertise to routinely conduct these appraisals and rely on self-assessment as a pragmatic approach to obtaining curriculum feedback and evaluation data. In this review, we describe three common designs for self-assessments: the pre-post, now-then, and post-only designs. We then give recommendations for choosing between each design to minimize bias. The choice of the best design is based on alignments with four considerations: (1) the educational objectives (e.g., demonstrate skill competency and/or change in skill level); (2) participants' prior experience and shared understanding of levels of skill performance; (3) the nature of the educational activity; and (4) available resources. For each design, we review strengths, weaknesses, and known biases and discuss examples to highlight trade-offs between options. We also discuss the use of control groups and follow-up surveys to measure retention over time as additional methods to address bias and related confounding. The guidance presented here is intended to raise educators' awareness of common pitfalls in self-assessment; minimize the impact of known biases when possible; provide evidence, examples, and rationales for optimal design choices; and increase the rigor of self-assessment evaluations.

Screening of metal-modified biochars for practical phosphorus recovery

The utilization of metal-modified biochars (MBCs) for practical phosphorus recovery has attracted significant research interest recently. However, the optimal choice of metals and modification methods for MBCs remains unclear. This study addresses this gap by comparing the phosphate adsorption capabilities of various MBCs using real municipal wastewater. The results show that zinc-modified biochar exhibits superior phosphate adsorption compared to biochars modified with calcium, magnesium, aluminum, and iron. Specifically, zinc-modified biochar prepared through metal-mediated biomass pyrolysis with alkaline soaking (ZnBC-OH) demonstrates the highest adsorption capacity, achieving 36.6 mg P/g in wastewater with a phosphate concentration of 5 mg P/L. This performance surpasses that of previously reported non-lanthanide modified biochars and is comparable to lanthanide-modified biochars. Mechanistic investigations reveal that the exceptional performance of ZnBC-OH is due to the presence of highly dispersed ZnO sites, which facilitate the formation of Zn3(PO4)2·4H2O precipitation, effectively retaining phosphate. Furthermore, a techno-economic analysis indicates that using ZnBC-OH in a fixed-bed column system can reduce phosphate levels from 6 mg L−1 to below 0.5 mg L−1 at a cost of 1.834 USD per ton of secondary treated wastewater, underscoring its promising application potential.

Effect of the connection structure of zirconia dental implants on biomechanical properties

The connection structure of zirconia dental implants significantly influences their biomechanical behavior and plays a crucial role in the overall service performance of the implant system. This study aims to compare the stress distribution of zirconia implants featuring various internal connection structures under different working conditions. Four distinct types of connection structures were designed for zirconia dental implants: triangular, quadrilateral, hexagonal, and hexalobular plus connections. Additionally, the finite element method was employed to analyze these structures under three working conditions: a static load test model, a bone level model, and a torsion model. Results indicated that in the static load test model, the hexagonal structure experienced the highest stress value at 1284.9 MPa due to its thin neck wall, whereas the hexalobular plus connected implant exhibited the lowest stress value at 1252.9 MPa. In the bone level model, the triangular connection structure demonstrated poor stress distribution for cortical bone and cancellous bone at 69.606 MPa and 7.8191 MPa, respectively. Conversely, the hexalobular plus connection yielded superior stress results for cortical bone and cancellous bone, with values of 69.606 MPa and 7.8191 MPa, respectively. In the torsion model, the hexalobular plus-connected implant exhibits the highest stress value at 210.37 MPa, while maintaining the smallest force transmission angle. Therefore, given that the abutment necessitates a greater range of installation angles and improved torque transmission, the hexalobular plus connection structure may represent the optimal choice.

The effects of counter ion on CO2 capture performance of amino acid salt solutions for direct air capture applications

Direct CO2 capture from the atmosphere has received growing attention driven by the imperative of achieving global net-zero emission targets. Amino acid salt solutions are promising candidates for liquid-based direct air capture processes. Utilised as a neutralized salt by reacting initially with hydroxides, it has been speculated that their performance may vary with the type of counter ion present in the solution. This work investigates the influence of counter ions, potassium, sodium, and lithium, of amino acid salt solutions on the physical properties, the CO2 absorption capacities, and the CO2 absorption kinetics under atmospheric CO2 concentration levels. The potassium-containing amino acid solutions exhibited significantly lower viscosities and mildly elevated densities compared to sodium- and lithium-containing ones. At 25 °C, the potassium-prolinate solution demonstrated the highest viscosity (8.5 mPa⋅s), whereas K-glycinate exhibited the lowest viscosity (2.5 mPa⋅s). Additionally, potassium-based solutions consistently displayed the highest CO2 mass transfer coefficients, followed by sodium- and lithium-containing ones. The CO2 mass transfer coefficient was highest for potassium-prolinate (2.99 mmol m−2⋅s−1⋅kPa−1) with the lowest rate observed for potassium-β-alaninate (1.68 mmol m−2⋅s−1⋅kPa−1). Interestingly, the type of counter ion had minimal impact on the CO2 absorption capacity, with potassium-based solutions exhibiting only a slightly elevated capacity compared to sodium- and lithium-based solutions. Specifically, potassium-lysinate displayed the highest CO2 absorption capacity (0.7 mol CO2 /mol amine), while potassium-β-alaninate showed the lowest (0.65 mol CO2/mol amine). It should be noted that all lithium-based solutions of all amino acids formed precipitates during CO2 absorption. From a practical and operational perspective, these findings suggest that the potassium salt solution of amino acids would be the optimal choice for direct air capture applications due to their enhanced solubility and CO2 mass transfer rates compared to the corresponding sodium and lithium counter ion salt solutions.

Investigation of Pozzolan Activity, Chemical and Granulometric Composition of Micro- and Nanosilicon of the Bratsk Ferroalloy Plant

The article presents the findings of a study conducted on a range of microsilicon grades selected at the Bratsk Ferroalloy Plant. The following analytical techniques were employed: X-ray fluorescence analysis, X-ray diffraction analysis, a granulometric composition study, and pozzolanic properties. The grades of the investigated microsilicon are compared with the furnace grade and the grade of the produced ferrosilicon. The findings of the research conducted at the Bratsk Ferroalloy Plant indicate that the microsilicon produced at the facility is suitable for use as an additive in the production of tires, artificial irregularities, and other rubber products intended for use on roads. In such applications, the quality and durability of the material are determined by its ability to withstand abrasion and wear. Therefore, it is essential to utilize the purest, most amorphous, and most finely dispersed silicon dioxide. The gas cleaning device GCD-4 FeSi-75 exhibits the greatest number of these parameters among the samples presented. Different samples of microsilica have a color from white to dark gray. The chemical and granulometric compositions were determined. The pozzolan activity was investigated. Based on the conducted analyses, it is possible to draw conclusions about the properties of materials and the potential for use in the construction industry for concretes of various values. The results of the analyses indicate that silicon dioxide with GCD-4 FeSi-75 is suitable for use in critical concrete structures. The quality of the silicon dioxide with GCD-4 FeSi-75 can be compared with that of Elkem 971. It is recommended that all the studied samples be employed as modifiers for cast iron, with the GCD-4 FeSi-75 sample being the optimal choice for testing in steels. The utilization of this modifier enables a reduction in the consumption of FeSi, exerting both an alloying and modifying effect on the melt. However, it is essential to emphasize the necessity for technological selection of the method of administration, as the powder, in its pure form, is susceptible to combustion and is not readily digestible. The quality of such a modifier, with a stable guaranteed effect, is comparable to the use of FeSi. Silicon dioxide plays an essential role in the production of refractories. The primary criteria for this industry are purity, the minimum content of the crystalline phase, and the activity of the material. It is recommended that the material from GCD-4 FeSi-75 be used in the production of refractories.

The Polyglot’s Playground: Navigating KMP, Flutter, and React Native in Cross-Platform Ecosystems

Abstract: This white paper compares three prominent cross-platform mobile development frameworks: Kotlin Multiplatform (KMP), Flutter, and React Native. Through analysis of key features, performance, development efficiency, community support, UI/UX capabilities, and learning curves, this study aims to guide developers and decision-makers in selecting the most appropriate framework for their projects. The paper scrutinizes each framework’s strengths and limitations based on extensive literature review and empirical testing. Key findings reveal that KMP excels in native performance and code sharing, Flutter facilitates rapid development with rich UI capabilities, and React Native offers a gentle learning curve with extensive community support. The optimal choice among these frameworks ultimately depends on project requirements, team expertise, and development priorities. As cross-platform development evolves, this paper equips readers with insights to make informed decisions in the dynamic mobile app landscape

A comparative study of two different doses of dexmedetomedine as an adjuvant to lignocaine in infiltration block for tympanoplasty: a triple-blinded, prospective, randomized controlled trial

Background: The ideal anesthetic drug choice for local infiltration anesthesia under monitored anesthesia care must provide a bloodless surgical field, along with analgesia and comfort for patients. We hypothesized that dexemedetomidine can provide better visibility of the surgical field at a higher dose of 1 µg/kg than 0.5 µg/kg, along with providing sedation and analgesia.Methods: After institutional ethics committee clearance and written informed consent, this prospective, randomized, triple blind study was conducted on ninety patients of either gender between 18 and 65 years who were scheduled for tympanoplasty under local infiltrative block and monitored anesthesia care. The patients were randomly assigned to either the dexmedetomidine (DEX) 0.5 group, who received a 10 ml solution containing 2% lignocaine and 0.5 µg/kg DEX, or the DEX 1.0 group, who received a 10 ml solution containing 2% lignocaine and 1 µg/kg DEX. The operative surgeon performed local infiltration using a specified and standardized 5-point infiltration technique around the auricle. The primary objective of this study was to compare the intraoperative bleeding at the surgical site by Boezzart’s scale. The comparison of normally distributed variables was conducted using the Student's t-test, whereas the comparison of non-normally distributed variables was performed using the Mann-Whitney U test. The analysis of qualitative data was conducted using the chi-square/Fisher's exact test. A P value less than 0.05 was considered statistically significant.Results: The overall bleeding score was significantly higher in the DEX 0.5 group (3.21 ± 0.727) than the DEX 1.0 group (1.43 ± 0.661) (P value < 0.001). The time to first analgesic requirement and surgeon satisfaction score were also significantly higher in the DEX 1.0 group.Conclusions: The combination of DEX at a dose of 1 µg/kg along with 2% lignocaine could potentially be considered the optimal choice for infiltration during tympanoplasty performed under monitored anesthetic care.

The Excellent Chemical Interaction Properties of Poloxamer and Pullulan with Alpha Mangostin on Amorphous Solid Dispersion System: Molecular Dynamics Simulation

Background: Alpha mangostin (AM) has demonstrated significant potential as an anticancer agent, owing to its potent bioactivity. However, its clinical application is limited by poor solubility, which hampers its bioavailability and effectiveness. Amorphous solid dispersion (ASD) presents a promising technique to enhance the solubility and stability of AM. Molecular dynamics simulation offers a rapid, efficient, and precise method to evaluate and optimize ASD formulations before production. Aim of Study: In this study, we conducted molecular dynamics simulations to explore the ASD development of AM with poloxamer and pullulan. Result: Our results revealed that AM–poloxamer complexes exhibit superior interaction characteristics compared to AM–pullulan, with a 1:5 ratio of AM to poloxamer and a cooling rate of 1 °C/ns demonstrating the most favorable outcomes. This combination showed enhanced hydrogen bonding, a more compact molecular structure, and higher stability, making it the optimal choice for ASD formulation. Conclusion: The integration of molecular dynamics simulation into ASD development significantly accelerates the formulation process and provides critical insights into achieving a stable and effective AM dispersion. The AM–poloxamer complex, particularly at a 1:5 ratio with a 1 °C/ns cooling rate, offers the best potential for improving AM solubility and therapeutic efficacy.

Investigation on Wireless Energy Harvesting Techniques for Internet of Things

The Internet of Things (IoT), by collecting, processing, and uploading information from its surroundings, makes the preliminary base for the construction of a smart city. To utilize IoTs fully, establishing wireless sensor networks (WSNs) as a subset technology of the system is pivotal. Among all energy sources, the radio frequency energy, with its extensive coverage, easy accessibility, and characteristic of being free of spatial limitations, is the optimal choice for energy harvesting [1]. This project aims to conduct a thorough investigation on a wideband wireless energy harvester with high efficiency and verify its application prospect in portable power sources. I have comprehensively studied and modeled the components of a wireless energy harvesting system. I further fabricated the wireless energy harvester based on the optimized circuit diagram. It successfully featured a high sensitivity of 2701 V/W at 1.05 GHz or a wide bandwidth ranging from 0.5 GHz to 2.5 GHz. Finally, I used the devised sensor in real-life scenarios and successfully powered a thermos hygrometer and a LED. I built a network of multiple energy harvesters with an in-situ monitoring system, analogous to the IoT. In this work, I have proposed a methodology to fabricate wireless energy harvesters with high sensitivity and wide bandwidth. This research will bridge the gap between the scientific exploration for novel devices and their application in real-life scenarios.

Pediatric B-cell Non-Hodgkin Lymphoma: The Impact of Therapy Response and Relapse on Outcome. A Single-center Analysis.

Pediatric patients with primary refractory or relapsed B-cell non-Hodgkin lymphoma (B-NHL) have highly unfavorable prognosis. In this study, we retrospectively analyzed outcomes in pediatric B-NHL patients treated in a single center in Poland from 1995 to 2022, with emphasis on therapy results in patients with progression or relapse. The primary objectives were a 5-year probability of overall survival (pOS) and a 5-year probability of event-free survival (pEFS). The secondary objectives involved the assessment of prognostic factors. A total of 76 children were eligible for the analysis. The 5-year pOS was 76.7%, and the 5-year pEFS was 72.9%. At diagnosis, elevated lactate dehydrogenase activity, the presence of B symptoms, bone marrow, skeletal or mediastinal involvement, and stage IV disease were associated with inferior outcomes. Nine children experienced progression and four relapse. The 5-year pOS for patients with progression was 38.1%. Two patients treated with hematopoietic stem cell transplantation (HSCT) as part of salvage therapy survived. However, only one out of seven patients who were treated without HSCT survived. The 5-year pOS was 0.0% in patients with relapsed disease. The most significant factor related to outcomes in pediatric B-NHL is therapy response, with a high mortality rate in children with refractory disease and relapse. There is no consensus on the salvage therapy approach; however, HSCT appears to be the optimal choice.

Effect of Blade Thickness on Hemodynamics and Hemolysis: A Case Study of Pediatric Centrifugal Blood Pumps.

Blood pumps have become popular whether for use as an implantable ventricular assist device or as extracorporeal membrane oxygenation. The quality of these pumps is assessed according to their ability to reduce the risk of blood damage thanks to an optimal choice of their geometric and operating properties. Lack of the research focused on the geometrical optimization of impellers has prompted this study. This study evaluated a computational and experimental analysis comparing the hemolytic performance of three centrifugal pumps. For this purpose, methods of Eulerian and Lagrangian are respectively used for hemodynamic and hemocompatibility investigations. Referring to the pediatric demands, these pumps function under clinically applicable pressure-flow conditions: 1 l/min of blood flow and a pressure differential of 60 mm Hg. These three pumps all use the same volute, but their impellers differ in terms of blade thickness. The objective is to examine how surface area affects the generation of hemolysis. In silico simulations were employed for both of the following tasks: first, identifying the distributions of velocities, pressures, and shear stresses; second, applying the Lagrangian approach to estimate the hemolysis index. Results showed the importance of the flow passage and the surface of the clearance on the hemocompatibility of the pumps. However, it was observed that there is not a linear effect of the blade thickness on the shear stress or index of hemolysis. Additionally, this work can provide information to develop an optimal design of a more hemocompatible blood pump.

A cost-effectiveness analysis of three surgical options for treating displaced femoral neck fractures in active older patients in Japan: A full economic evaluation.

For older patients with displaced femoral neck fractures, in which primary osteosynthesis is usually not indicated, there are three primary prosthetic options-bipolar hemiarthroplasty (BHA), single-bearing total hip arthroplasty (SB-THA), and dual-mobility THA (DM-THA). However, the optimal choice for managing displaced femoral neck fractures remains controversial. Accordingly, this study aimed to evaluate the cost-effectiveness of BHA, SB-THA, and DM-THA in active older patients with displaced femoral neck fractures. A decision tree combined with a Markov model was employed to analyze the cost and quality-adjusted life years (QALYs) of BHA, SB-THA, and DM-THA for the management in the Japanese healthcare system. By simulating the five-year trajectory of a 75-year-old woman treated for a displaced femoral neck fracture, the cost-effectiveness of the three surgical options was evaluated. One-way sensitivity analysis and probabilistic sensitivity analysis (PSA) were used to assess parameter uncertainty. Additionally, two scenario analyses were conducted for other settings. The treatment was considered to be cost-effective when the incremental cost-effectiveness ratio (ICER) was below the 5,000,000 yen/QALY threshold. Compared with BHA, SB-THA exhibited higher costs but greater health benefits, resulting in an ICER of 1,499,440 yen/QALY. DM-THA offered additional health benefits compared with SB-THA, with an ICER of 4,145,777 yen/QALY. One-way sensitivity analysis revealed some influential parameters. PSA indicated that the probability of DM-THA, SB-THA, and BHA being cost-effective was 40.1%, 38.5%, and 21.4%, respectively. SB-THA was more cost-effective than BHA in patients aged 65-85 years, while DM-THA was more cost-effective than SB-THA in patients aged 65-75 years. The results suggest that SB-THA is a cost-effective alternative to BHA for displaced femoral neck fractures in active older patients, whereas DM-THA is more cost-effective than SB-THA in relatively younger patients. It is, therefore, recommended that orthopedic surgeons select the most appropriate surgical option based on the individual patient's physiological age.

Hybrid Multi-Criteria Decision Making for Additive or Conventional Process Selection in the Preliminary Design Phase

Additive manufacturing (AM) has become a key topic in the manufacturing industry, challenging conventional techniques. However, AM has its limitations, and understanding its convenience despite established processes remains sometimes difficult, especially in preliminary design phases. This investigation provides a hybrid multi-criteria decision-making method (MCDM) for comparing AM and conventional processes. The MCDM method consists of the Best Worst Method (BWM) for the definition of criteria weights and the Proximity Index Value (PIV) method for the generation of the final ranking. The BWM reduces the number of pairwise comparisons required for the definition of criteria weights, whereas the PIV method minimizes the probability of rank reversal, thereby enhancing the robustness of the results. The methodology was validated through a case study, an aerospace bracket. The candidate processes for the bracket production were CNC machining, high-pressure die casting, and PBF-LB/M. The production of the bracket by AM was found to be the optimal choice for small to medium production batches. Additionally, the study emphasized the significance of material selection, process design guidelines, and production batch in the context of informed process selection, thereby enabling technical professionals without a strong AM background in pursuing conscious decisions.

Total resection via right mini-thoracotomy for left atrial myxoma in juvenile Carney complex: a case report

BackgroundCarney complex is a rare syndrome characterized by skin pigmentation, endocrine disorders, and myxomas. It is particularly notorious for its tendency to exhibit aggressive cardiac myxomas. Herein, we present a case of a juvenile female patient diagnosed with Carney complex who underwent a right lateral mini-thoracotomy.Case presentationA 13-year-old girl presented with sudden-onset left hemiplegia and dysarthria. Magnetic resonance imaging revealed multiple areas of restricted diffusion. Echocardiography identified a tumor in the left atrium, suspected to be related to Carney complex based on her medical history and physical examination findings. Surgery was performed via right lateral mini-thoracotomy, which minimized the risk of embolism and ensured a cosmetically favorable outcome. The left atrial wall defect was repaired with autologous pericardium. At 3 years postoperatively, follow-up echocardiography indicated no tumor recurrence and normal cardiac function.ConclusionsOngoing follow-ups are essential due to the aggressive nature of the Carney complex and its high recurrence rates. Right lateral mini-thoracotomy offers the advantage of avoiding re-sternotomy and minimizing adhesion dissection, making it the optimal choice for this case.

The algorithm and choice of the optimal tool for endoscopic removal of a foreign body from the gastrointestinal tract in children.

BACKGROUND: Suspicion of a foreign body (FB) is one of the most common reasons for performing an upper gastrointestinal (GI) endoscopy in children. In our opinion, the development of a new algorithm and the choice of optimal equipment will ensure timely diagnosis and success of endoscopic FB removal from the GI tract in children. AIMS: to develop an algorithm and select the optimal equipment to ensure timely diagnosis and safety of endoscopic FB removal from the GI tract in children. METHODS: a retrospective three-center study of children’s medical histories with suspected GI FB’s from 2017 to 2020. The analysis included: the patient's age, presence, localization, type of FB, visibility on X-ray, the time elapsed before its removal, the type and effectiveness of the endoscopic instrument (EI), duration, success and complications of the procedure. RESULTS: 1,173 children were examined (boys n=676, 57.6%; girls n=497, 42.4%) average age 3.5 years (±3.3, 0-17 years). The diagnosis of GI FB was confirmed in 1008 (86.1%) patients, and endoscopic examination was performed in 756 (75%) cases. The majority of FB were radiopaque (n=844, 83.7%) and had inorganic nature (n=941, 93.4%). According to the pathological effect: inert FB (n=637, 63.2%), chemical (disk batteries, n=166, 16.5%), mechanical (pointed, food bolus, bezaors, hydrogel balls, n=143, 14%), physical (magnets, n=62, 6.2%) effects on the child's body. According to localization, in 273 (27%) children, FB was located in the esophagus, 471(46.8%) in the stomach, 23 (2.2%) in the duodenum, 250 (24%) migrated from the upper GI tract. FB’s were endoscopically removed in 751 (99.3%) cases out of 756 conducted intraluminal examinations. The most in-demand EI turned out to be a gripping device of the "net" type (n=283, 37.6%), rat tooth forceps and a loop (both n=278, 37%), to a lesser extent biopsy forceps (n=86, 11.5%), a basket (n=50, 6.5%), forceps “alligator" (n=43, 5.7%) and in 10 (1.3%) free-lying FB’s were gently pushed down by an endoscope from the esophagus to the stomach. Net, “rat tooth” forceps, loop and basket turned out to be the most versatile EI’s for removing four types of FB’s, with the best average time of the procedure. There were no complications related to the FB’s endoscopic removal. Adverse events related to FB – 52 (5.1%) cases: 51 chemical burns of the esophagus(n=17) and stomach (n=34) with disc batteries, 1 perforation of the stomach due to prolonged exposure to magnets. CONCLUSIONS: the proposed modification of the algorithm for FB removal from the GI tract, the optimal choice of endoscopic equipment and manipulation accessories depending on the age of the child, localization, type and harmful effects of the swallowed object are the key to its successful and effective extraction in children.

Numerical investigations of heat transfer and pressure drop in packed bed duct exposed to forced convection boundaries under local thermal non-equilibrium conditions

The present study is a 2-D numerical study which discusses the thermohydraulic performance of packed bed duct under local thermal non-equilibrium and steady state conditions exposed to forced convection boundaries (BC-6). The numerical model is well validated with the experimental work reported in the literature and found to be accurate enough to perform further parametric investigations. The analysis is done to see the effect of different ball diameter (5 mm, 9 mm and 11 mm), bed porosity, heat transfer fluid (air, water and engine oil - Pr = 0.70–645) and ball material (EPS, steel and bronze) on heat transfer and fluid flow characteristics in turbulent flow region of Reynolds number ranging from 900 to 14,320. The numerical results obtained using commercial CFD software COMSOL shows that, the heat transfer coefficient and pressure drop in packed bed increases with increase in ball diameter, thermal conductivity of ball and bed porosity which is exactly reverse as reported in literature for BC-1 to BC-5. The maximum thermal performance factor with bronze particles is 2.45 and 24.5 times more than stainless steel and EPS particles respectively for larger particle size and bed porosity. Engine oil exhibits significantly higher heat transfer coefficient (9.7 × 105 W/m2K) and pressure drop (3.3 × 106 Pa) compared to water (40,126 W/m2K and 2028 Pa) and air (600 W/m2K and 250 Pa) respectively. Overall, the combination of water as heat transfer fluid along with bronze particles of larger diameter and larger bed porosity emerges as the optimal choice for enhancing heat transfer in the packed duct exposed to forced convection boundary condition BC-6.