Optimal Level Research Articles

Biomass to biofuel: Palm kernel shells as catalyst supports for enhanced biodiesel production

AbstractThe use of agricultural biomass fibers, specifically palm kernel shell (PKS), has significant potential to enhance biodiesel production. This approach overcomes economic barriers and contributes to sustainability by repurposing agricultural biomass. This study explores the effectiveness of PKS as a cost‐effective and sustainable catalyst support. Palm kernel shell was chosen due to its high carbon content, low ash presence, and abundance as a byproduct in the palm oil industry, making it an economically viable and environmentally friendly option. In this study, an optimized activated carbon from PKS biomass was fabricated as catalyst support to enhance biodiesel production efficiency. Using response surface methodology (RSM), the PKS was impregnated with phosphoric acid and synthesized at various acid concentrations, impregnation times, and activation times to enhance porosity for catalytic support capabilities. The experimental design included a central composite design (CCD) to vary these factors systematically and determine their optimal levels. Scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analysis revealed significant development of porosity, affirming the efficient activation process. Energy dispersive X‐ray (EDX) analysis confirmed phosphorus incorporation during activation, indicating the formation of an intricate pore structure. Fourier transform infrared (FTIR) spectroscopy highlighted the presence of functional groups pertinent to the biodiesel reaction process. The transesterification process employing PKS as a catalyst with different biobased feedstocks, such as waste frying oils from corn, palm, and sunflower, led to biodiesel yields of varying efficiencies. Notably, corn oil had the highest yield at 94.92%. This study highlights the potential of PKS as a biobased catalyst support and contributes to the broader biorefinery concept by integrating biomass utilization into renewable fuel production.

IMPLEMENTASI METODE DELPHI TERHADAP TUGAS AKHIR MATAKULIAH TEFL

In the era of globalization and rapid technological development. To prepare students to face social changes, the world of work and rapid technological advances, student competencies must be improved and prepared to face the demands of the times. and these optimal and relevant skills must be considered in the Teaching English as a Foreign Language (TEFL) course. Microteaching in TEFL courses must be adapted to the demands of the times. Therefore, the Delphi Method can be used to form guidelines and predict trends. The five main uses of Delphi in higher education, include: cost effectiveness, cost-benefit analysis, curriculum and campus planning, university education goals and objectives, generalized futuristic education goals and objectives. This research uses a descriptive qualitative method with a literature study approach. Keywords in qualitative research, namely, the process of understanding, and humans. both natural phenomena and man-made phenomena. These phenomena can be activities, and the difference between one phenomenon and another. This is indicated by the results of the standard deviation which has reached the optimal level. Based on the results of the priority sequence reference, it can be determined that students are required to record microteaching practices. themselves, and upload it to YouTube and then report it to the lecturer. YouTube's selection policy is based on this platform not limiting the length of the video, so students can be as creative as possible in class.

The Impact of Cross-Border Banking on Financial Stability

The globalization of financial markets has ushered in an era of interconnectedness, where financial institutions increasingly operate across national borders. This phenomenon, known as cross-border banking, has both potential benefits and risks for financial stability. While it can enhance risk diversification and promote economic growth, it also poses challenges such as contagion effects and regulatory coordination issues. This study aims to comprehensively investigate the impact of cross-border banking on financial stability, particularly within the European Union (EU). By examining the costs and benefits, developing metrics to measure optimal integration, and applying these metrics to EU countries, this research seeks to provide policymakers and regulators with valuable insights into the management of cross-border banking activities. The study begins by analysing the costs and benefits of cross-border banking. While it can offer advantages like risk spreading and increased credit stability, it also introduces risks such as contagion and regulatory challenges. The research explores the interplay between these factors and their implications for financial stability. To quantify the optimal level of cross-border banking integration, the study develops forward-looking indicators. These metrics aim to measure the extent to which a country's banking system is integrated into international markets while minimizing risks. By applying these indicators to EU countries, the research identifies which countries are more susceptible to systemic risks and which ones demonstrate optimal practices. Furthermore, the study investigates the systemic risks associated with cross-border banking, particularly the risk of financial contagion. It examines how the interconnectedness of financial institutions can facilitate the spread of shocks across borders and explores the role of regulatory coordination in mitigating these risks. The research also evaluates the trade-off between cross-border banking integration and local financial stability. While integration can provide diversification benefits, it can also increase vulnerability to external shocks. The study seeks to determine the optimal level of integration that allows countries to benefit from international markets without compromising domestic stability. Finally, the study provides policy recommendations based on its findings. By identifying countries with imbalances or low diversification, the research offers guidance on how to improve financial stability through targeted interventions. The recommendations aim to enhance the resilience of cross-border banking systems and contribute to a more stable and efficient global financial landscape.

On the Machinability and Formation of Gas Film Thickness in ECDM of Silica based Pyrex Glass

Abstract Electrochemical discharge machining (ECDM) stands out as a preferred method for microfluidic channel fabrication due to its ability to produce required shapes with the least thermal damage along with close tolerances and dimensional accuracy. Recently, there has been significant progress made in the domain of ECDM for parametric analysis, focusing on discharge regime characteristics, but precise control of the hydrodynamic regime remains a challenge. We analyzed the effect of various auxiliary electrodes on the formation of gas film thickness and discharge energy during the fabrication of microchannels using ECDM on silica-based Pyrex glass under varying conditions. Experiments were conducted on an ECDM setup to achieve near damage-free edges of microchannels on the surface silica-based Pyrex glass. Results show the effect of various auxiliary electrodes, applied voltage, and electrolyte concentration on gas film thickness, spark energy, rate of material removal (MRR), and width of overcut (WOC). The optimum parametric level of applied voltage, electrolyte concentration, and auxiliary electrode were 68V, 35wt%, and A2 auxiliary electrode, respectively and the best response values were 0.4134mg/min, and 40μm, respectively, for MRR and WOC. In addition, tool wear rate, heat affected zone, and surface morphology of fabricated microchannels was examined using scanning electron microscopy, optical microscope, and energy-dispersive X-ray spectroscopy

AI-based green technology implementation simulation for achieving carbon neutrality: exploring the role of subsidies and knowledge management.

This study investigates the role of green technology implementation (GTI) based on artificial intelligence (AI) at the household level to achieve carbon neutrality by addressing gaps in the existing research. The research focuses on understanding how education on green consumption preferences, green invention and emission impacts can optimally influence AI-based GTI decisions. Through behavioural analysis at the household level, this study quantifies the effects of education and preferences on emissions and proposes subsidies as accelerators for carbon-neutral transitions. Furthermore, the study employs regression analysis and simulation-based optimisation, which are then validated against prior methodologies, with a focus on Punjab, Pakistan. Utilising a simple random sampling technique, approximately 1000 households were surveyed to represent the province's diverse demographics comprehensively. Findings reveal that higher education levels correlate with less enthusiasm for AI-based GTI. Simulations measured optimal subsidy levels by striking a balance between encouraging green behaviour and technological adoption. By integrating diverse factors and AI-based GTI optimisation, this study defines important thresholds for education and subsidies, thus highlighting their pivotal role in advancing AI-based green technologies and sustainable household practices. This research significantly enhances the understanding of the complex relationship between AI-based GTI decisions and educational influences, thereby contributing to the advancement of environmental sustainability.

Non-linear association of the platelet/high-density lipoprotein cholesterol ratio with bone mineral density a cross-sectional study

BackgroundNumerous studies have demonstrated shared risk factors and pathophysiologic mechanisms between osteoporosis and cardiovascular disease. High-density lipoprotein cholesterol (HDL-C) and platelets have long been recognized as crucial factors for cardiovascular health. The platelet to HDL-C ratio (PHR) combines platelet count and high-density lipoprotein cholesterol (HDL-C) level, It is a novel biomarker for metabolic syndrome and cardiovascular disease. The platelet to HDL-C ratio (PHR) possibly reflects the balance between proinflammatory and anti-inflammatory states in the body. Therefore, we hypothesized that changes in PHR ratios may predict a predisposition to pro-inflammatory and increased bone resorption. However, the relationship between the platelet to HDL-C ratio (PHR) and bone mineral density (BMD) remains insufficiently understood. This study aimed to elucidate the relationship between the platelet to HDL-C ratio (PHR) index and bone mineral density (BMD).MethodsData from the NHANES 2005–2018 were analyzed, excluding adults with missing key variables and specific conditions. Nonlinear relationships were explored by fitting smoothed curves and generalized additive models, with threshold effects employed to calculate inflection points. Additionally, subgroup analyses and interaction tests were conducted.ResultsThe study included 13,936 individuals with a mean age of 51.19 ± 16.65 years. Fitted smoothed curves and generalized additive models revealed a nonlinear, inverted U-shaped relationship between the two variables. Threshold effect analysis showed a significant negative association between PHR and total femur bone mineral density (BMD) beyond the inflection point of platelet to HDL-C ratio (PHR) 33.301. Subgroup analyses showed that a significant interaction between these two variables was observed only in the age and sex subgroups (P-interaction < 0.05).ConclusionsOur study identified a complex, nonlinear, inverted U-shaped relationship between platelet to HDL-C ratio (PHR) and total femur bone mineral density (BMD). These findings underscore the importance of maintaining optimal PHR levels to support bone health, especially in high-risk populations.

Extending behavioral theory of the firm to new ventures: Dispositional optimism as a moderating influence on new product introductions in high-tech ventures

Extant literature has typically drawn from the behavioral theory of the firm (BTOF) to examine new product introductions in the context of well-established companies. This paper extends the behavioral theory of the firm to entrepreneurial firms and argues that jointly considering founders' dispositional optimism together with the performance feedback promises to yield a better understanding of new product introductions in new ventures. We analyze a longitudinal dataset on the activities of 344 newly founded high technology ventures in the United States. The key insight of our study is that when BTOF is applied to the context of nascent, entrepreneurial ventures, the personality and dispositional characteristics of the entrepreneur must be considered. Specifically, we find that performance attainment discrepancy leads to new product introductions, but only when the entrepreneur's dispositional optimism level is high.

Microstructural analysis and prediction of strength response of black expansive soil

Amelioration studies using waste residues are gaining popularity in the construction sector, as they offer dual effective management and utilization of waste residue. This practice is of interest to the growth of any nation due to environmental protection and the economic advantages it offers. For that reason, this present-day study seeks the sustainable utilization of calcium carbide residue (CCR) and palm oil fuel residue (POFR) in expansive soil amelioration. After an in-depth characterization of the parent soil, several number of California bearing ratio (CBR) tests was performed on the parent and additive-treated soil. For this purpose, a total of twenty mixes were prepared possessing various combinations of CCR, POFR, water, and soil. CBR testing for soaked and unsoaked conditions was carried out to assess the strength performance and effectiveness of the additives. Through this approach, optimal California bearing ratio (CBR) values of 41 and 61% were achieved at trial runs designated Y4 for soaked and unsoaked conditions, indicating a strong mechanical performance. These experimental outcomes were subsequently validated using statistical indicators such as ANOVA (F crit > F) and student t-test (t crit > t stat). A step further, microstructural testing such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were performed on the natural soil and soil treated with the optimal level of additives obtained at trial runs designated Y4. The SEM micrographs evidence the transformation of the loosely packed structure of untreated soil into a dense soil composite. Similarly, diverging molecular functional groups were recorded in the FTIR examination with the incorporation of blended CCR-POFR. Finally, the findings suggest that carefully designed mixtures of CCR and POFR can offer a sustainable, efficient approach to soil amelioration, potentially revolutionizing construction practices.

OPTIMAL DECISION-MAKING FOR NEWSPAPER INVENTORY: BALANCING DEMAND UNCERTAINTY AND PROFITABILITY

Estimating cost-benefit analysis, calculating the real value of anything before buying it is essential in order to know if this purchase is fetching or not. In the industry of selling newspapers, since demand is determined by various unpredictable features like news quality and types of reader interest, it may be difficult to estimate how many copies you should buy daily. On the other hand, this study addresses the classic Newsvendor Problem by analyzing a single-period inventory management model to find the optimal order quantity that maximizes profit. Simulating different demand scenarios up to 20 days into the future, using financial-based assumptions (e.g.: selling price, buying cost, and salvage value) on order quantities in order to investigate profits. The results show that we can identify the optimal level of order quantity in the cost-benefit analysis and profit analysis under different demand situations. This method reduces both excess waste and missed sales opportunities, making an optimal answer for inventory alignment in sought-after uncertainty-based industries. The insights of this analysis are not just relevant to newspaper sales but also to all comparable industries where accurate inventory management becomes challenging.

Fertilized soils enhance the efficiency of phytoremediation by tropical grasses in cadmium-contaminated soils

The effectiveness of phytoremediation in Cd-contaminated soils is crucial for enhancing nutrient availability and plant tolerance to Cd. We simulated soil contamination with varying textures and fertilization conditions. Two experiments were conducted: one without liming and fertilization and another with soil fertilization for grasses. The soil types used were Oxisol and Entisol, and the grasses tested were Megathyrsus maximus and Urochloa brizantha at three Cd levels: 0 mg kg−1 (Control), 2 mg kg−1 (Low), and 12 mg kg−1 (High). Soil amendments and fertilization did not significantly change Cd availability. Soil chemical attributes were unaffected by Cd contamination but were influenced by fertilization, which kept the pH below optimal levels. Cd availability was higher in more contaminated soils, with Entisol showing greater concentrations than Oxisol. Dry matter production of the grasses decreased with higher contamination, with U. brizantha being more productive than M. maximus in fertilized soils. Cd accumulation was higher in highly contaminated soils, particularly for U. brizantha. The bioconcentration factor was higher in Entisol, while the translocation factor exceeded 1.0 only for M. maximus in low-contamination Oxisol. Fertilization can mitigate Cd contamination effects, with U. brizantha showing greater tolerance and accumulation capacity in fertilized soils.

China’s interdependent positioning in the semiconductor global value chain

ABSTRACT The semiconductor global value chain (GVC) which was established by global lead companies and their strategic suppliers is now facing significant disruption because of geopolitical tensions between the US and China. As semiconductor production became offshored to East Asia, China’s growing market for semiconductors associated with its role as a major electronics assembly location facilitated its integration into the global value chain for lower value added functions such as assembly and packaging. Together with its high level of optimisation, the GVC is also characterised by significant oligopolies of intellectual property resulting in an overall asymmetric interdependence between locations in advanced and emerging regions. Because of the vital role of the semiconductor sector in areas of national security and within the technology sector more widely, China seeks to develop greater self-reliance in semiconductors at a time when its integration in the global value chain is facing significant threats.

307 Use of defatted black soldier fly larvae meal (BSFLM) as an alternative and functional ingredient in canine nutrition

Abstract Black soldier fly (Hermetia illucens) larvae meal (BSFLM) is an alternative, sustainable, and nutrient-rich ingredient for pet foods. However, limited information is available on optimal inclusion levels and its functional properties. The objective of the study was to evaluate the effects of incremental levels of BSFLM (15% or 30%) as a partial or full substitute for chicken by-product meal (CM) in extruded diets. Three complete and balanced diets were formulated and extruded: Control, 15% BSFLM, and 30% BSFLM. The effects of the diets on nutrient digestibility, fecal metabolites and microbiota, and serum oxidative stress and inflammatory biomarkers in adult dogs were examined. A complete randomized design was used with adult Beagles (n = 10/treatment). The experimental period lasted 70 d, consisting of a 14-d adaptation to the control diet followed by 56-d test period. Data were analyzed using SAS Proc Mixed 9.4 with P ≤ 0.05 significance. All diets were well-accepted by the dogs; food intake and fecal output were not affected (P &amp;gt; 0.05) by treatment. Apparent total tract digestibility (ATTD) of dry matter, crude protein, and fat did not differ among treatments, whereas ATTD of organic matter (81.2%) and total dietary fiber (18.9%) was less (P &amp;lt; 0.05) for dogs fed 30% BSFLM in contrast with the Control group (83.2% and 30.3%, respectively). Fecal concentrations of total short-chain fatty acids and total phenols were less (P &amp;lt; 0.05) for dogs fed 30% BSFLM relative to dogs fed Control. No treatment effect was observed for serum biomarkers of oxidative stress and inflammation. Fecal microbial diversity differed between Control and 30% BSFLM groups. Overall, extruded diets containing 15% or 30% were well-digested by dogs as demonstrated by similar ATTD coefficients compared with Control. Intrinsic presence of chitin in BSFLM, and other insect-derived ingredients, can behave like insoluble dietary fiber in a food matrix, which would explain the decreased ATTD for organic matter and total dietary fiber, as well as less fecal concentration of total short-chain fatty acids. The inclusion of 30% BSFLM may have decreased protein hindgut fermentation due to less fecal concentration of total phenols. Altogether, the inclusion of 15% BSFLM resulted in similar physiological responses in comparison with dogs fed the Control diet. Greater inclusion levels of BSFLM may impact ATTD, however, it also has the potential to modulate fecal metabolites and microbiota, without negatively affecting fecal microbial richness.

130 Meta-analysis of the impact of Quebracho and Chestnut tannin extract supplementation on the growth performance in growing and finishing beef cattle

Abstract Integrating tannin extracts (TE) into the diet of growing and finishing beef cattle has shown promise in optimizing protein utilization while potentially mitigating methane emissions. Despite these potential benefits, there is a notable gap in a comprehensive analysis of the influence of TE on growth rate. This study addressed this gap by collecting data on the supplementation of a blend of condensed (from Schinopsis spp.) and hydrolyzable (from Castanea spp.) tannins, which has about 70% total tannins, and its impact on critical metrics, such as average daily gain (ADG, kg/d), dry matter intake (DMI, kg/d), and feed efficiency ratio (FER, g/kg). Our objective was to conduct meta-regression analyses to understand better the nuanced effects of condensed tannin supplementation on the overall performance of beef cattle during the critical stages of growth and finishing. The dataset was constructed by collecting published studies that reported in vivo experimental data on growing and finishing beef cattle supplemented with different levels of TE. It contained 132 observations from 35 publications. The meta-analysis was conducted by linear regression with a mixed-effects model fitted by the restricted maximum likelihood method using the nlme package of R software (ver. 4.3.1). Studies were assumed as random variables, and their interaction with the intercept and slope were included in the regression. The number of animals per treatment was used as a study-specific weight. Studies accounted for 32%, 35%, or 27% of the total variance when regressing ADG, DMI, or FER, respectively, on TE (% DM). After adjusting for random effects, the ADG increased (P &amp;lt; 0.001) with increasing levels of dietary TE (P &amp;lt; 0.001): 1.344 (± 0.0071) + 0.240 (±0.0298) × TE (n = 99, r2 = 0.40). It was observed that as the dietary TE level increased, its impact on the ADG tended to decrease from 0.33 kgּ d-1ּ % TE-1 when fed up to 0.5% TE to 0.24 kgּ d-1ּ % TE-1 when fed up to 1.5% TE, suggesting a possible nonlinear relationship between these two variables. Similarly, DMI decreased slightly (P &amp;lt; 0.001) at 0.61 kg/d/% TE, but with a lower precision (n = 115, r2 = 0.14). Consequently, FER increased (P &amp;lt; 0.001) at 17 kgּ d-1ּ % TE-1 (n = 93, r2 = 0.34). Initial findings suggest that incorporating TE into the diet of growing and finishing cattle, up to a concentration of 0.5% DM, positively influences the growth rate and enhances FER while minimally affecting DMI. Subsequent research endeavors should delve into a more intricate examination of optimal TE inclusion levels and explore additional performance indicators for a comprehensive understanding of its impact.

SHANK3 depletion leads to ERK signalling overdose and cell death in KRAS-mutant cancers

The KRAS oncogene drives many common and highly fatal malignancies. These include pancreatic, lung, and colorectal cancer, where various activating KRAS mutations have made the development of KRAS inhibitors difficult. Here we identify the scaffold protein SH3 and multiple ankyrin repeat domain 3 (SHANK3) as a RAS interactor that binds active KRAS, including mutant forms, competes with RAF and limits oncogenic KRAS downstream signalling, maintaining mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) activity at an optimal level. SHANK3 depletion breaches this threshold, triggering MAPK/ERK signalling hyperactivation and MAPK/ERK-dependent cell death in KRAS-mutant cancers. Targeting this vulnerability through RNA interference or nanobody-mediated disruption of the SHANK3–KRAS interaction constrains tumour growth in vivo in female mice. Thus, inhibition of SHANK3–KRAS interaction represents an alternative strategy for selective killing of KRAS-mutant cancer cells through excessive signalling.

On the strategic choice of overconfident lawyers

This paper analyzes how the plaintiff selects her lawyer based on lawyers’ confidence in their trial-effort productivity. The plaintiff’s lawyer works on a contingent fee and makes litigation decisions on the plaintiff’s behalf. When the lawyer’s preferences are decisive at both the settlement and the trial stage, the plaintiff must anticipate that a more confident lawyer evaluates settlement compared to trial differently and implies different equilibrium trial effort levels. When the lawyer implements the plaintiff’s ideal settlement demand, only the influence of the confidence level on trial effort levels is relevant. In both cases, the plaintiff prefers an overconfident lawyer but would be harmed by excessive overconfidence. In many circumstances, the optimal confidence level maximizes the plaintiff’s trial payoff. However, when the lawyer’s preferences are decisive at both the settlement and trial stage, the plaintiff may choose an even more confident lawyer to raise the settlement level her lawyer demands from the defendant.

Effects of Maltodextrin–Fructose Supplementation on Inflammatory Biomarkers and Lipidomic Profile Following Endurance Running: A Randomized Placebo-Controlled Cross-Over Trial

Background: Managing metabolism for optimal training, performance, and recovery in medium-to-high-level endurance runners involves enhancing energy systems through strategic nutrient intake. Optimal carbohydrate intake before, during, and after endurance running can enhance glycogen stores and maintain optimal blood glucose levels, influencing various physiological responses and adaptations, including transitory post-endurance inflammation. This randomized trial investigates the impact of a high-dose 2:1 maltodextrin–fructose supplementation to medium-to-high-level endurance runners immediately before, during, and after a 15 km run at 90% VO2max intensity on post-exercise inflammatory stress. Methods: We evaluated inflammatory biomarkers and lipidomic profiles before the endurance tests and up to 24 h after. We focused on the effects of high-dose 2:1 maltodextrin–fructose supplementation on white blood cell count, neutrophil number, IL-6, cortisol, and CRP levels, as well as polyunsaturated fatty acids, ω-3 index, and AA/EPA ratio. Results: This supplementation significantly reduced inflammatory markers and metabolic stress. Additionally, it may enhance the post-activity increase in blood ω-3 fatty acid levels and reduce the increase in ω-6 levels, resulting in a lower trend of AA/EPA ratio at 24 h in the treated arm. Conclusions: Adequate carbohydrate supplementation may acutely mitigate inflammation during a one-hour endurance activity of moderate-to-high intensity. These effects could be beneficial for athletes engaging in frequent, high-intensity activities.

Dietary condensed tannin supplementation improves growth performance and feed utilization of juvenile Largemouth bass (Micropterus salmoides) through positively regulating serum lipids and intestinal health

Considering the diverse biological activities of condensed tannin (CT), the study aimed to evaluate the effect of CT on growth performance and intestinal health in juvenile largemouth bass (Micropterus salmoides) through a 56-day feeding trial. Largemouth bass (5.99 ± 0.03 g) were fed a basic diet supplemented with different levels of CT: 0 g/kg (the control group, CG), 0.60 g/kg (the T0.6 group), 1.50 g/kg (the T1.5 group), 3.75 g/kg (the T3.75 group), and 9.38 g/kg (the T9.38 group). The results indicated that dietary supplementation of CT at 3.75 g/kg promoted growth performance, feed conversion ratio, the apparent digestibility coefficients (ADCs) of crude protein and crude lipid, the crude protein of whole-body, the intestinal antioxidant capacity, and intestinal immune response, as well as the development of intestinal villi (P < 0.05), while the fish fed with 9.38 g/kg CT exhibited the opposite trend. Further, dietary CT (3.75 g/kg) decreased crude lipid in the whole-body compared to the CG (P < 0.05). Dietary CT (3.75 g/kg) altered the microbial community, the relative abundance of Bacillus and Lysinibacillus were increased compared to the CG. Additionally, the serum metabolome results revealed a negative correlation between Lysinibacillus abundance and lipid metabolites in the serum. These findings suggested that supplementing the diet with 3.75 g/kg CT promoted the growth performance, feed utilization, and intestinal health of largemouth bass. The optimum CT level was 4.15 g/kg based on second-order polynomial regression analyses of weight gain rate.

No Free Lunch? Welfare Analysis of Firms Selling through Expert Intermediaries

Abstract We study how firms target and influence expert intermediaries. In our context, pharmaceutical manufacturers provide payments to physicians during promotional interactions. We develop an identification strategy based on plausibly exogenous variation in payments driven by differential exposure to spillovers from academic medical centers’ conflict-of-interest policies. Using a case study of an important class of cardiovascular drugs, we estimate heterogeneous effects of payments on prescribing, with firms targeting highly responsive physicians. We also develop a model of supply and demand, which allows us to quantify how oligopoly prices reduce drug prescribing, and how payments move prescribing closer to the optimal level, but at great financial cost. In our estimated model, whether consumers are harmed by payments depends on whether there is substantial under-prescribing due to behavioral or other frictions. In a final exercise, we calibrate such frictions using clinical data and estimate that payments benefit consumers in this case study.

A Cancer Subpopulation Competition Model Reveals Optimal Levels of Immune Response that Minimize Tumor Size.

Breast cancer is a complex disease with significant phenotypic heterogeneity of cells, even within a single breast tumor. Emerging evidence underscores the significance of intratumoral competition, which can serve as a key contributor to cancer drug resistance, imparting substantial clinical implications. Understanding the competitive dynamics is paramount as it can significantly influence disease progression and treatment outcomes. In the present work, a mathematical model was developed using a system of differential equations to describe the dynamic interactions between two cancer subtypes (each further classified into cancer stem cells and tumor cells) and innate immune cells. The purpose of the model is to comprehensively understand the competitive interactions between the heterogeneous subpopulations. The equilibrium points and stability analysis for each equilibrium point were established. Model simulations showed that the competition between two cancer subtypes directly affects the number of both species. When competition between two cancer subtypes is strong, increasing the immune response rate specific to the more competitive species effectively reduces the tumor size. However, if the competition is relatively weak, an optimal immune response rate is required to minimize the total number of tumor cells. Rates below the optimal level fail to reduce the population of the stronger species, whereas rates above the optimal level can lead to the recurrence of the weaker species. Overall, this model provides insights into breast cancer dynamics and guides the development of effective treatment strategies.

黄芪离散元仿真参数的标定与试验

This study is based on the discrete element method to calibrate the physical parameters of astragalus membranaceus. Plackett Burman test, steepest climb test, and Box Behnken test were used to screen for significant influencing factors and optimal levels, and a quadratic regression model was obtained for the relative error between the simulated and physical experiment resting angles. The results showed that the relative error between the simulated and physical test angles of repose was only 0.392%, which can provide a theoretical basis for the discrete element simulation test of the working process of the astragalus membranaceus picking machine.