Complex Index Research Articles

Model of Growth of the Region’s Economy Based on the Index of Economic Complexity

Model of Growth of the Region’s Economy Based on the Index of Economic Complexity

The role of agroforestry in solving the agricultural landscapes vulnerabilities in the Po Plain district

AbstractThe current trend of biodiversity deterioration in rural systems is a complex issue that operates across multiple spatial scales. Agroforestry practices have the potential to positively contribute towards addressing these trends by shaping the structure of agricultural landscapes and their underlying ecological functions. This study aims to test a multi-scale analytical approach to understand and account for these processes. Specifically, the study seeks to assess the contributions that agroforestry practices at the farm scale can make towards supporting biodiversity, in response to the wider-scale landscape eco-mosaic structural and functional challenges and requirements (both at the local and extra-local landscape systems). To achieve this, a series of landscape ecology analyses are conducted on an agroforestry-based rice farm located in the western Po Plain region of Northern Italy. These analyses examine various landscape structural traits (such as matrix composition, patch size, shape complexity, and diversity indices) and functional traits (including connectivity and bionomic indices), with different levels of detail for each scale of analysis. This allows for the evaluation of the current ecological status of both the extra-local and local scale landscape systems (including drivers of vulnerability and resilience) and the assessment of the farm's current contributions to biodiversity support. Based on these findings, strategic agroforestry interventions are identified at the farm scale to enhance its capacity to address the wider-scale ecological gaps. Two design scenarios are assessed, wherein functional ecological traits such as landscape diversity, connectivity, and ecological stability are improved. The results confirm the role of farm scale agroforestry management as a buffering tool, demonstrating how it contributes to the restoration of broader-scale landscape vulnerabilities. The applied approach provides cost-effective assessments of biodiversity-related ecological processes, with the accuracy of the findings dependent on the comprehensive multi-scale analysis conducted.

Nexus of natural resources exploitation, social protection, and sustainable environment: COP27 is a sufficient solution?

A pervasive threat regarding human health, ecological balance, progress, and sustainability marks the current era. Many nations are grappling with the consequences of climate change and global warming caused by excessive carbon emissions from various harmful activities. Consequently, while some nations face resource constraints, they also work hard to keep the environment clean and green to promote sustainable growth. Concerns about the effects of climate change and global warming have recently shifted the focus of national governments and policymakers. Furthermore, these issues take center stage in developed nations due to the scarcity of natural resources, leading to increased carbon emissions. This research uses a panel data set that covers the top 20 developed countries from 2000 to 2021 to examine the relationship between nature's bounty (NAT) and welfare (SP) and carbon emissions (CO2). The next-generation panel assembly root test verified that all indicators were stationarity at the first difference, and the cross-sectional dependence (CSD) mirrored the panel countries' CSD. The second-generation cointegration technique (Wester Lund and Edgerton) was used to find an equation involving the variables. The rigorous check by the Cup-BC test and long-run empirical estimates from the Cup-FM estimation highlighted that technical innovation, social protection, and higher levels of green energy contribute to greater environmental sustainability and lower CO₂ emissions. Environmental quality declines and CO2 emissions rise in developed countries due to population, natural resource availability, and economic complexity index. The study's results may illuminate the reasons for environmental deterioration and propose solutions.

Evaluating malocclusion patterns in children with autism spectrum disorder using the index of complexity, outcome and need: a cross-sectional study

BackgroundThe purpose of this study was to evaluate the complexity of malocclusion and existing patterns in children with autism spectrum disorders (ASD) using the index of complexity, outcome and need (ICON).MethodsThis cross-sectional study included children diagnosed with ASD, aged 9–15 years. A group of healthy children with the same demographic characteristics was randomly selected as the control group. Malocclusion was assessed according to ICON scoring protocol. The following parameters were recorded: dental aesthetics, upper arch crowding/spacing, presence of crossbite, anterior-vertical relationship (open and deep bite) and buccal segment anterior-posterior relationship. Finally, an overall ICON score was derived and reported for each patient. Descriptive analysis was performed for all investigated variables. Significance level was set at p < 0.05.ResultsA total of 324 children, divided into ASD (162) and control (162) groups, comprised the study population. Our results demonstrated that the average overall ICON score was significantly higher in the ASD group compared to the control group (38.77 vs. 27.43, p < 0.001). ASD children also obtained significantly higher scores regarding the dental aesthetics component (3.84 vs 2.78, p < 0.001). Study groups were significantly different in terms of the prevalence of incisor overbite and open bite (p = 0.002 and p < 0.001, respectively). Patients in the ASD group showed a higher prevalence of Class II and Class III malocclusions (p < 0.001).ConclusionASD children obtained significantly higher overall ICON scores, indicating more complex and severe malocclusions. These children also exhibited a greater tendency towards Class II and III malocclusions.

Soundscape characteristics of RAS tanks holding Atlantic salmon (Salmo salar) during feeding and feed withdrawal

Behavioural monitoring can provide crucial information on welfare and feeding in aquaculture. Passive acoustic monitoring of behaviour can be particularly useful in recirculating aquaculture systems (RAS), as they often have turbid water that impairs visual monitoring. Currently, little is known about the sounds that make up the soundscapes in RAS tanks holding Atlantic salmon (Salmo salar). In this study, hydrophones were used to continuously record the soundscape in eight single tank RAS holding Atlantic salmon parr for 15 days, with the fish in four of the tanks being fasted by feed withdrawal for five days from the sixth to the tenth day. The results show that soundscapes in RAS tanks are affected by feeding. Two main sound sources were identified during feeding in RAS tanks, one related to pellets delivery and the other to fish behaviour. The sound of pellets hitting the water surface had energy concentrated at frequencies between 1.7 and 4.0 kHz, with peak frequency decreasing and amplitude increasing with increasing number of pellets hitting simultaneously. The feeding sounds of Atlantic salmon had energy concentrated at frequencies between 6.5 and 9.4 kHz.More complex soundscapes were recorded during feeding events. These were characterized by variations in amplitude and frequency that have been described by using acoustic indexes in RAS tanks for the very first time. The Acoustic Complexity Index (ACI), the Acoustic Entropy Index (H) and the Normalized Difference Soundscape Index (NDSI) showed distinct changes in the soundscape related to feeding events; ACI increased while H and NDSI decreased compared to the times in between scheduled feeding times. The sound types identified in this study and the outcomes of the acoustic indices indicate a possibility to monitor system performance as well as fish behaviour in the tank soundscapes in RAS. Soundscape monitoring can contribute to match feeding closer to fish appetite, improve water quality, and reduce risks that deviations in the system performance can have on fish welfare during production.

Capability identification for new charging station into distribution system with electric, economic and traffic considerations

The shift of conventional vehicles to electric vehicles (EVs) is on pace nowadays. Increment in EVs adoption eventually results as increment of load on the existing power distribution system. This increment can adversely affect the performance of the distribution system. Location of electric vehicles charging station (EVCS) in the distribution system requires more technical finding before moving on into it. Implementation needs attention for several aspects like electric profile, economics, and traffic management and so, this work considers all of them. The impact of charging stations (EVCS) on operating parameters of the distribution network such as voltage stability, reliability and power losses are investigated by the proposed formulation of a Voltage Stability-Reliability-Power Loss (VRP) indices in this work. This index has the capabilities of considering voltage stability, reliability, and power loss under a single frame. The capabilities of the system with random load changes are compared with the base system without increments in load. This presented work gives assurance about the EV based load increment capabilities in the existing system without compromising with distribution system constraints. The main contribution of the proposed work is to examine the impact of voltage sensitivity, system stability, power losses, reliability measures, and a complex VRP index on choosing locations for EV charging stations and its effects on the existing system. Also, to ensure accurate results, these factors are assessed across seven distinct load scenarios, contributing significantly to the ongoing research in this field.

A comprehensive study of Tianma Toutong Tablets from the dual dimensions of quality and efficacy using fingerprint techniques and network pharmacology

BackgroundThe quality of traditional Chinese medicine (TCM) is the prerequisite for ensuring its safe and effective clinical application. With the increasing popularity of TCM worldwide, the quality control of TCM products has become increasingly crucial. Tianma toutong tablet (TMTTT) is mainly used for migraine caused by external wind and cold, blood stasis, or deficiency of blood and nourishment. However, the mechanism of action of TMTTT is still unclear, and there has been a lack of in vitro antioxidant activity research and migraine treatment mechanism research. Therefore, it is urgent to establish a set of comprehensive and effective evaluation methods. Resultsthree fingerprint profiles were established using HPLC, UV, and DSC analysis methods, and established three digital parameters simple complexity index (SX), simple clarity index (SY), simple complexity clarity ratio (Sω), 22 batches of samples were evaluated using a comprehensive linear quantitative fingerprint method (CLQFM). In addition, the antioxidant activity of the samples was determined using the DPPH method, and the relationship between fingerprint peaks in different fingerprints and antioxidant capacity was explored using Pearson correlation coefficients. Finally, network pharmacological research was conducted to investigate the potential targets, compounds, and pathways involved in the treatment of migraines with TMTTT. The results showed that the 22 batches of samples were classified into different quality grades. TMTTT exhibited good antioxidant activity, the fingerprint-efficacy relationship showed that gastrodin, chlorogenic acid, ferulic acid, imperatorin and isoimperatorin had strong antioxidant capacity, providing directions for the identification of active compounds. A total of 36 core targets were identified and screened by network pharmacology, which AKT serine/threonine kinase 1 (AKT1), albumin (ALB), insulin (INS), tumor necrosis factor (TNF), prostaglandin-endoperoxide synthase 2 (PTGS2) and interleukin-6 (IL-6), and compounds such as β-sitosterol, chrysophanol, vanillin are the key to the treatment of migraine, providing references for subsequent clinical research and new drug development. Significance: This study examined the consistency of the quality of TMTTT and the mechanism of action in treating migraines from both quality and efficacy perspectives, providing a favorable direction for further research on TMTTT and offering new ideas for the quality control of TCM compound formulations.

Collaborative management of environmental pollution and carbon emissions drives local green growth: An analysis based on spatial effects

Collaborative management of environmental pollution and carbon emissions (CMPC) has been a major policy instrument to promote Sustainable Development Goals (SDG) in recent years. However, the relationship between the benefits and drawbacks of this environmental management practice for green growth in and around a local area remains to be clarified. Using 30 provinces in China during 2001–2019 as the object of analysis, we assessed the efficiency of local CMPC practices using the nonradial directional distance function (NDDF) model, predicted local green growth using the frontier green complexity index (GCI), and empirically examined the spatial effects, locational heterogeneity, and threshold characteristics of the relationship using the spatial Durbin model and the panel threshold model. Our study finds that although efficient CMPC does drive local green growth, the promotion effect is nonlinear with decreasing marginal effect. This effect is particularly obvious in economically developed regions with higher CMPCs, which will absorb resources from neighboring regions and create a "siphoning" effect. It was found that local financial support and foreign direct investment (FDI) can radiate green growth to neighboring regions; therefore, CMPC practice needs to pay more attention to the effect of joint governance, supplemented by financial and foreign investment policy tools, to better promote the green transformation of local economy.

EFL students' syntactic complexity development in argumentative writing：A latent class growth analysis (LCGA) approach

The study explored EFL students' development of syntactic complexity by employing the Latent Class Growth Analysis (LCGA) approach. A total of 214 tertiary EFL students from Southwest China were invited to write four argumentative essays over an academic semester. The unconditional models of LCGA were utilized to explore the optimal latent classes of students' development trajectories of syntactic complexity. The conditional models of LCGA were employed to investigate the predictive effect of English proficiency on the optimal latent classes. Results of the unconditional models revealed different latent classes of development trajectories for six indices of syntactic complexity rather than the remaining ones, which offers tentative evidence for the heterogeneity of L2 development trajectories. Results of the conditional models showed that English proficiency did not predict the membership in these latent classes. These results are discussed and implications for L2 instruction are attempted.

Discrepancy index, treatment complexity index and objective Grading system: correlation between parameters, indices and implications for treatment

Abstract Objectives An assessment of orthodontic treatment duration and results allows for measurable outcomes, goal-setting, and the establishment of patient management standards. It is important information that can be utilised for educational purposes in an orthodontic postgraduate program. The aim of this study was to determine correlations of the parameters within and between the Objective Grading System (OGS), Discrepancy Index (DI) and Treatment Complexity Index (TCI) and identify those factors associated with treatment outcomes and duration. Materials and methods This retrospective cohort study involved a consecutive sampling of 242 pre- and post-treatment patient records from the postgraduate orthodontic clinic between 2013 and 2017. The cases were assessed using the DI, OGS, and TCI pre-treatment. Treatment outcomes were assessed using the OGS. Spearman’s Rank Correlation Coefficients were computed within and between the indices. Multiple and logistic regressions were used to evaluate associations between treatment outcomes and duration, respectively. Results Within DI, significant correlations (p &lt; 0.05) were observed between overjet-overbite, overjet-occlusal relationship, overjet-crowding, overbite-anterior open bite, overbite-crowding, anterior open bite-lateral open bite, anterior open bite-crowding, lingual posterior cross bite-crowding. Within pre-OGS, significant correlations (p &lt; 0.05) were observed between alignment-marginal ridge, alignment-occlusal relationship, alignment-root angulation, overjet-interproximal contact, marginal ridge-buccolingual inclination, marginal ridge-overjet, marginal ridge-occlusal contact, marginal ridge-occlusal relationship, overjet-occlusal contact, overjet-occlusal relationship, overjet-root angulation, occlusal relationship-root angulation, interproximal contact-root angulation. Within TCI, functional appliance correlated with orthognathic surgery (p &lt; 0.001), rapid palatal expansion (RPE) (p = 0.005) and multidisciplinary collaboration (p = 0.001). Pre-OGS correlated with DI (p &lt; 0.001) and TCI (p = 0.026). Cephalometric (p = 0.002) and other conditions (p = 0.031) were associated with treatment outcomes. RPE was associated with extended treatment duration (p = 0.014). Conclusions DI, OGS, and TCI exhibited weak correlations within and between indices. Cephalometric values, clinical conditions, and RPE use should be carefully considered during treatment planning.

The Relationship between Commercial, Technological, Research (Multidimensional) Complexity Indices and Financial Development

The source of economic growth is the supply-demand balance. Demand refers to consumption and supply refers to production. Producing quality products plays an important role on the production side of this balance. The country, which has a wide range of qualified products called sophisticated products, continues to grow with financial development. The concept of economic complexity refers to product diversity. This concept has taken its place in the literature by being expanded into commercial, technological, and research complexity indices as the content of the multidimensional complexity index. In this study, the relationship between multidimensional complexity indices and financial development indicators of E7 (Emerging) countries (Brazil, China, India, Indonesia, Mexico, Russia, Turkey) is analyzed with Gengenbach, Urbain, and Westerlund Cointegration Test and Mean Group Estimator applied in case of cointegration. It has been determined that these variables are cointegrated, and this relationship between the commercial and technological complexity index and financial development is significant. As a result of the analysis with the mean group estimator, it was concluded that the technological complexity index has a greater impact on financial development than the commercial and research complexity indices.

Tailoring starch-lipid complexes for optimized flaxseed oil emulsion stability, antioxidation, and digestion kinetics

Whereas starch-lipid complex emulsifiers are anticipated to possess both an outstanding amphiphilicity and slowly-digesting characteristics, yet a more sustainable and cost-effective approach remains to be explored. Herein, we systematically prepared starch-lauric acid complexes (SLACs) through a solid encapsulation method under varying reaction temperatures (50–90 °C) and times (0.25–60 h). Complexing index analysis, differential scanning calorimetry, and X-ray diffraction analysis revealed an enhanced degree of complexation in SLACs with prolonged reaction time, evidenced by the inward migration of free lauric acid, as further confirmed by confocal laser scanning microscopy. In vitro digestibility, contact angle, and interfacial tension measurements demonstrated that SLACs exhibited high levels of slowly digestible starch, a low digestion rate, and excellent amphiphilicity, which was particularly notable in SLACs produced at 80 °C for 6 h. Emulsions stabilized by SLACs showed a smaller droplet size, a higher oil loading rate, an increased yield stress, and an improved storage stability compared to V-type starch. Oxidation experiments indicated that SLACs enhanced the oxidative stability of flaxseed oil, with elevated initial oxidation temperatures and reduced levels of oxidative products. In a simulated gastrointestinal digestion model, SLACs-stabilized structured emulsions exhibited sustained release and lower final contents of fatty acids, suggesting superior resistance to bile acids and digestive enzymes compared to PG2000, a chemically modified food starch (i.e. OSA-starch) refined from waxy maize. Our findings provide an effective strategy for enhancing lipid antioxidation and regulating intestinal digestion.

Factors Associated with Hyperpolypharmacy and Complex Medication Regimens in Kidney Transplant Recipients.

Background: Kidney transplantation is considered the best modality for renal replacement therapy. The use of immunosuppressive therapy and pre-existing and newly developed comorbidities predispose these patients to the use of a large number of medications. (Hyper)polypharmacy is associated with worse adherence and negative outcomes. This study aims to explore the factors correlated with hyperpolypharmacy and complex medication regimens in kidney transplant recipients. Methods: This is a cross-sectional study of outpatient kidney transplant recipients. Collected data include demographic data, complete chronic medication lists, medical history, and graft function. Linear and logistic regression were used to identify factors associated with hyperpolypharmacy and complex medication regimens. Medication regimen complexity was quantified by the Medication Regimen Complexity Index (MRCI). Results: Overall, 224 kidney transplant recipients were included, with an average time since transplantation of 8 years. Hyperpolypharmacy was present in more than two-thirds of patients; the average number of different medications was 12; and the mean MRCI score was 21.4, ranging from 6 to 50. Hypertension was almost universally present, while other frequently prescribed medication groups were hypolipemics, medication for bone-mineral metabolism disorders, gout, and antihyperglycemics. Conclusions: Factors independently associated with hyperpolypharmacy and complex medication regimens were found to be age and graft function. Studies investigating interventions aimed at reducing medication complexity and increasing adherence should focus on older patients with worse graft function.

The Influence of Economic Complexity Index on Income Inequality in G20 Forum Countries

This research examines the influence of the economic complexity index, GDP per capita, gross higher education participation ratio, government spending on education, and fertility rates on income inequality in G20 Forum member countries from 2010 to 2019. The dynamic panel data regression method with the two-step System Generalized Method of Moments (SYS-GMM) estimation technique is used to analyze the data in this study. The findings reveal that the economic complexity index, GDP per capita squared, government spending on education, and fertility levels have a negative and significant effect on income inequality. Meanwhile, GDP per capita and gross enrollment rates in tertiary education have a significant positive effect on income inequality. This study shows that the economic complexity index and the quality of human resources can reduce income inequality. Therefore, policies that focus on improving the quality of human resources need to be considered to encourage innovation, increase GDP per capita, and ultimately reduce income inequality.

Factors Influencing Adherence to Treatment in Adult Patients with Hypertension

Introduction Adherence to treatment including medication and lifestyle modification is crucial for improving health outcomes in patients with hypertension. However, there is limited research investigating the factors influencing adherence to medication and lifestyle modification, particularly among adult patients diagnosed with hypertension. Objective To investigate adherence to treatment and the predictive power of work status, comorbidity, complexity of medication regimens, perceived severity and risk of hypertension complications, and quality of care affecting adherence to treatment in adult patients with hypertension. Design Cross-sectional correlational predictive research using the multidimensional adherence model as the conceptual framework. Methodology The sample included 156 adult patients with essential hypertension aged 18 to 59 years old who had received antihypertensive medication and lifestyle modification treatment for at least six months at a super-tertiary hospital’s hypertension clinic. Data were collected between April and July 2023. The research instruments consisted of a general profile questionnaire, a treatment adherence questionnaire for patients with hypertension, a perceived severity and risk of hypertension complications questionnaire, a patient assessment of chronic illness care, the Charlson Comorbidity Index, a medication regimen complexity index, and an illness record form. These instruments were examined for content validity by experts and tested for reliability prior to use in data collection. The reliability ranged from .77-1.00. The data were analyzed using descriptive statistics and multiple linear regression. Results The sample had an average age of 46.50 years (SD = 9.65); 63.46% were female. The average score for adherence to treatment was 87.97 (SD = 9.02), with the highest score for average medication adherence of 34.37 (SD = 2.52) and the lowest score for average exercise adherence of 4.33 (SD = 1.89). Additionally, 14.74% were overweight, and 71.80% were obese. The majority were employed (83.33%), without any comorbidities (62.82%), and had a low level of medication regimen complexity (68.59%). Furthermore, they demonstrated a high level of perceived severity and risk of hypertension complications (96.15%) and reported a high level of quality of care (61.54%). In the Multiple linear regression, 30.9% of the variance in adherence to treatment was explained (Adjusted R2 = .309 F(5,150) = 14.858, p &lt; .001). Work status (β = -.262, p &lt; .001), comorbidity (β = -.184, p = .020), perceived severity and risk of hypertension complications (β = .466, p &lt; .001), and quality of care (β = .165, p = .017) together were significant predictors of adherence to treatment in adult patients with hypertension. Recommendation To promote adherence to treatment in adult patients with hypertension, nurses should develop strategy to improve quality of care within hypertension clinics and enhance the perceived severity and risk of hypertension complications as well as enhance lifestyle modifications particularly regarding diet and exercise for overweight and obese adults with hypertension.

Experience in Processing Alternative Crude Oils to Replace Design Oil in the Refinery

A comprehensive investigation of a highly complex petroleum refinery (Nelson complexity index of 10.7) during the processing of 11 crude oils and an imported atmospheric residue replacing the design Urals crude oil was performed. Various laboratory oil tests were carried out to characterize both crude oils, and their fractions. The results of oil laboratory assays along with intercriteria and regression analyses were employed to find quantitative relations between crude oil mixture quality and refining unit performance. It was found that the acidity of petroleum cannot be judged by its total acid number, and acid crudes with lower than 0.5 mg KOH/g and low sulphur content required repeated caustic treatment enhancement and provoked increased corrosion rate and sodium contamination of the hydrocracking catalyst. Increased fouling in the H-Oil hydrocracker was observed during the transfer of design Urals crude oil to other petroleum crudes. The vacuum residues with higher sulphur, lower nitrogen contents, and a lower colloidal instability index provide a higher conversion rate and lower fouling rate in the H-Oil unit. The regression equations developed in this work allow quantitative assessment of the performance of crucial refining units like the H-Oil, fluid catalytic cracker, naphtha reformer, and gas oil hydrotreatment based on laboratory oil test results.

Treatment plan complexity quantification for predicting gamma passing rates in patient-specific quality assurance for stereotactic volumetric modulated arc therapy.

To investigate the beam complexity of stereotactic Volumetric Modulated Arc Therapy (VMAT) plans quantitively and predict gamma passing rates (GPRs) using machine learning. The entire dataset is exclusively made of stereotactic VMAT plans (301 plans with 594 beams) from Varian Edge LINAC. The GPRs were analyzed using Varian's portal dosimetry with 2%/2mm criteria. A total of 27 metrics were calculated to investigate the correlation between metrics and GPRs. Random forest and gradient boosting models were developed and trained to predict the GPRs based on the extracted complexity features. The threshold values of complexity metric were obtained to predict a given beam to pass or fail from ROC curve analysis. The three moderately significant values of Spearman's rank correlation to GPRs were 0.508 (p < 0.001), 0.445 (p < 0.001), and -0.416 (p < 0.001) for proposed metric LAAM, the ratio of the average aperture area over jaw area (AAJA) and index of modulation, respectively. The random forest method achieved 98.74% prediction accuracy with mean absolute error of 1.23% using five-fold cross-validation, and 98.71% with 1.25% for gradient boosting regressor method, respectively. LAAM, leaf travelling distance (LT), AAJA, LT modulation complexity score (LTMCS) and index of modulation, were the top five most important complexity features. The LAAM metric showed the best performance with AUC value of 0.801, and threshold value of 0.365. The calculated metrics were effective in quantifying the complexity of stereotactic VMAT plans. We have demonstrated that the GPRs could be accurately predicted using machine learning methods based on extracted complexity metrics. The quantification of complexity and machine learning methods have the potential to improve stereotactic treatment planning and identify the failure of QA results promptly.

Non-dimensional parameters governing the crashworthy performance of tubes with complex cross-sections

The crashworthiness of thin-walled tubes with various designs under axial compression has been extensively investigated. Despite this, the parameters that govern the performance of tubes and can be applied across different cross-sectional topologies have not hitherto been available. In this paper, twenty types of thin-walled tubes with different cross-sectional shapes (e.g., multi-celled, bi-tubular, and hierarchical square, hexagonal and circular tubes) have been numerically simulated and theoretically analysed. All the tubes are made from identical material and possess identical apparent cross-sectional area, height and mass. Six indicators are employed to characterise the crashworthiness performance of the tubes. Two novel non-dimensional indices, the geometric complexity index (RG) which is the ratio of the total length of solid segments in the cross-section of a tube to that of the square tube, and the topological index (RT) which is the non-dimensional coefficient in the expression of plastic energy dissipation closely related to the types and numbers of the wall junctions in cross-section, are identified for the first time. Both the indices RG and RT are used in a regression analysis of the indicators that characterise the crashworthiness of the tubes. The results reveal that the crashworthiness indicators of the tubes, the mean crushing force (MCF), the specific energy absorption (SEA) and the effectiveness of energy absorption (EEA) do not exclusively vary with RG. Instead, MCF, SEA and EEA are all properly fitted by linear relations with a single non-dimensional parameter ω, which is a simple function of RG and RT, i.e., ω=RT/RG. Increasing the magnitude of ω ultimately improves the crashworthiness of tubes, including enhanced specific energy absorption, effectiveness of energy absorption and crushing force efficiency, while reducing the force fluctuation during the crushing process. Of the tubes studied, the edge-based hierarchical circular tube (EH_C) has the highest SEA of 22.17 J/g, which is 133%, 60% and 41% larger than that of single-celled square, hexagonal and circular tubes, respectively.

Increase in forest structural complexity along a precipitation gradient is mediated by partial harvests in temperate Patagonian forests

Increasing forest structural complexity is becoming a common goal in forestry worldwide. However, the lack of empirical quantification clouds its implementation. Here we quantified the long-term effects (> 30 y) of partial harvest on stand structural complexity and net primary productivity using the east–west precipitation gradient (318–2508 mm, mean annual precipitation-MAP) of western Patagonian as a study system. In this gradient, pairs of 1-ha plots on 20 sites (20 plots harvested and 20 plots unharvested) were installed. In each plot terrestrial laser scanning was used to quantify the stand structural complexity index (SSCI), and Sentinel satellite images to obtain the Enhanced Vegetation Index (EVI: proxy of net primary productivity). Generalized linear mixed-effect models were used to relate SSCI to MAP and EVI to SSCI, with harvesting as indicator variable, and site as random variable (two plots nested to same precipitation). Results showed that harvested plots on mesic-to-humid sites (but not on dry sites) had higher SSCI and EVI values compared to unharvested plots, likely due to a greater vertical canopy packing. These results show the influence of precipitation on SSCI, which resulted in a more diversified stand structure and higher EVI. Such insights support site-specific management aimed to increase forest structural complexity.

On spectral inclusion sets and computing the spectra and pseudospectra of bounded linear operators

In this paper, we derive novel families of inclusion sets for the spectra and pseudospectra of large classes of bounded linear operators, and establish convergence of particular sequences of these inclusion sets to the spectrum or pseudospectrum, as appropriate. Our results apply, in particular, to bounded linear operators on a separable Hilbert space that, with respect to some orthonormal basis, have a representation as a bi-infinite matrix that is banded or band-dominated. More generally, our results apply in cases where the matrix entries themselves are bounded linear operators on some Banach space. In the scalar matrix entry case, we show that our methods, given the input information we assume, lead to a sequence of approximations to the spectrum, each element of which can be computed in finitely many arithmetic operations, so that, with our assumed inputs, the problem of determining the spectrum of a band-dominated operator has solvability complexity index one in the sense of Ben-Artzi et al. (2020). As a concrete and substantial application, we apply our methods to the determination of the spectra of non-self-adjoint bi-infinite tridiagonal matrices that are pseudoergodic in the sense of Davies [Commun. Math. Phys. 216 (2001), 687–704].