Search Results (20)

We study the shape of the Bachelier-implied volatility of a spread option on two assets following correlated local volatility models. This includes the limiting case of spread options on two correlated Black–Scholes (BS) assets. We give an analytical result for the at-the-money (ATM) skew of the spread-implied volatility, which depends only on the components’ ATM volatilities and skews. We also compute the ATM convexity of the implied spread option for the case when the assets follow correlated BS models. The results are extracted from the short-maturity asymptotics for basket options obtained previously by Avellaneda, Boyer-Olson, Busca and Friz and, thus, become exact in the short-maturity limit. Numerical testing of the short-maturity analytical results under the Black–Scholes model and in a local volatility model show good agreement for strikes sufficiently close to the ATM point. Numerical experiments suggest that a linear approximation for the spread Bachelier volatility constructed from the ATM spread volatility and skew gives a good approximation for the spread volatility for highly correlated assets. Full article

This study evaluated the synergistic effects of microbial decomposition agents and deep rotary tillage on rice straw decomposition, soil nutrient dynamics, and microbial communities in paddy fields of southern China. A two-factor randomized block experiment was conducted, with straw decomposition dynamics modeled using a modified Olson decay model, and microbial communities were assessed via high-throughput sequencing and network analysis. The combined treatment significantly increased the decomposition rate constant, reduced the time for 50% decomposition to 81 days, and enhanced soil nutrient availability, especially total nitrogen, phosphorus, and potassium. Microbial richness, diversity, and network complexity were also improved. Structural equation modeling indicated that nutrient availability, rather than microbial α-diversity, was the main driver of decomposition processes. These findings suggest that integrating microbial agents with deep tillage offers an effective strategy for optimizing straw return, improving soil fertility, and enhancing microbial functional resilience in rice systems. Full article

The automotive industry’s rapid expansion has made the development of lightweight, high-strength automotive steels essential for both energy efficiency and emission reduction. Among these materials, Fe-Mn-Al-C steel has drawn considerable interest due to its favorable combination of low density and high strength. This research examines the impact of Nb alloying (with Nb content of 0% and 0.5%) and solution treatment on the microstructure and mechanical properties of cold-rolled Fe-28Mn-10Al-C low-density steel. Various methods were employed, including Thermo-Calc thermodynamic simulations, the Olson–Cohen model, X-ray diffraction (XRD), metallographic microscopy, room-temperature tensile testing, and scanning electron microscopy (SEM). The findings demonstrate that Nb alloying significantly refines the austenite grain structure of the Fe-28Mn-10Al-C steel, improving both strength and ductility in comparison to the 0Nb steel. After solution treatment at 1050 °C for 30 min, the cold-rolling-induced defects are effectively removed, leading to a substantial increase in elongation at fracture (38.14–44.45%) and an ultimate tensile strength exceeding 900 MPa. As the solution treatment temperature increases, the austenite grains coarsen, and the number of twins increases, while yield strength and ultimate tensile strength decrease. However, there is a notable enhancement in ductility, with the material exhibiting a ductile fracture mechanism. These results offer valuable insights and a theoretical foundation for further improving the mechanical properties of Fe-Mn-Al-C low-density steels. Full article

The austenitic–martensitic transformation in austenitic–ferritic duplex stainless steel CF8 subjected to cold plastic deformation with a deformation degree ε = 10–95% is studied here using transmission Mössbauer spectroscopy (MS), conversion electron Mössbauer spectroscopy (CEMS), and X-ray diffraction (XRD) methods. It is assumed that the α′-martensite phase appeared at ε > 10%. The CEMS results showed that the formation of α′-martensite occurred most intensively in the near-surface layers of the steel, distributing in depth with the growth of the deformation degree. The volume fraction of the α′-martensite was determined based on the results of calculations carried out via the MS and XRD methods, and a good correlation was observed. A modified Olson–Cohen model was proposed to determine the dependence of the amount of α′-martensite on the deformation degree ε. The coefficients included in the Olson–Cohen expression were found. Full article

In the global ecosystem, the slow decomposition of coniferous forest litter has caused a number of ecological problems, among which is the decay of China’s Pinus massoniana litter. It has been pointed out that converting pure P. massoniana plantations into mixed forests with broadleaf species can improve ecosystem services. Therefore, the selection of mixed species is key for the success or failure of the conversion of near-natural forests. In this study, from the perspective of apoplastic decomposition, the leaf litter of P. massoniana was mixed with three common native broadleaf species, namely Choerospondias axillaries, Cinnamomum camphora, and Cyclobalanopsis glauca, using an indoor incubation method to systematically analyse the differences in the decomposition rates of apoplastic material in each mixture, and to provide a theoretical basis for the selection and mixing of tree species for the management of near-natural forests in P. massoniana forests. After 175 days of indoor incubation of the foliar litter under dark conditions at 25 °C, the residual dry matter of the mixed apoplastic litter of P. massoniana and the three broadleaf trees was lower than that of P. massoniana. It indicated that the incorporation of broadleaf apoplastic foliage promoted litter decomposition, with the most pronounced effect in the case of admixture with C. Camphora. Compared with the group of pure P. massoniana alone, the remaining mass and residual rate decreased by 0.56 g and 9.45%, respectively. The regression equation of Olson’s negative exponential decay model showed that the P. massoniana + C. Camphora mixture had the fastest decomposition rate (k) of 1.305, an increase of 0.237, a decrease in half-life of 0.11 years, and a decrease in turnover period of 0.49 year, compared to the P. massoniana alone group. Most of the measured values throughout the incubation period were significantly lower than the predicted values, suggesting that there was a non-additive and synergistic effect of litter mixing. Full article

Introduction: Although gifted children can express high cognitive skills, they can also show socioemotional difficulties. Drawing from Olson’s circumplex model, the present paper assessed the role of family functioning in internalizing and externalizing problems in gifted children. Materials and Methods: 362 mothers and their 362 gifted children were included. The unbalanced subscales of the FACES IV—disengagement, enmeshment, rigidity, and chaos—and the CBCL were administered to mothers. The children completed the WISC-IV. Results: The model predicting internalizing problems was significant and explained 5.6% of the variance. Only rigidity had an independent and positive effect on internalizing problems in gifted children over and above sociodemographic variables and QI, whereas disengagement, enmeshment, and chaos were not associated with internalizing problems. The model predicting externalizing problems was significant and explained 10% of the variance. Again, rigidity was the only variable that had an independent and positive effect on externalizing problems in gifted children over and above sociodemographic variables and QI, whereas disengagement, enmeshment, and chaos were not associated with externalizing problems in this population. Discussion: Rigid families with a low ability to change in conditions that require readjustment appear to increase the risk of both internalizing and externalizing problems in gifted children. Although further studies are needed to support these preliminary findings, parental support interventions aimed at increasing flexibility appear to be useful. Full article

The decomposition of mangrove litter plays a crucial role in material circulation and energy flow within mangrove forests. Evaluating the decomposition-based variation in biogenic elements in litter is important for improving our understanding about their biogeochemical cycling in ecosystems. The main objective of this study was to examine the interaction effect during the decomposition process of mixed Kandelia obovata and Avicennia marina litter. Variations in C and N were also determined in the decomposing leaf litter mixtures. Our findings revealed that the decomposition rates were faster in summer than in winter, and increased with the proportion of A. marina litter. After 35 days of decomposition in summer, the remaining weights for different proportions of K. obovata (KO) and A. marina (AM) were 22.9% (KO:AM = 1:2), 27.2% (KO:AM = 1:1), and 31.2% (KO:AM = 2:1), respectively. Similarly, after 49 days of decomposition in winter, the remaining weights for the different KO:AM proportions were 27.7%, 35.4%, and 44.0%, respectively. Additionally, the decomposition of mixed K. obovata and A. marina litter had an influence on C content and N release dynamics. These results provide a scientific basis for understanding the decomposition of mixed mangrove litter and its implications for material circulation and energy flow within these ecosystems. Full article

Glioblastoma is a highly aggressive brain tumor that has a poor prognosis despite various treatments like surgery, chemotherapy, and irradiation. However, a restricted ketogenic diet (RKD), which has been proven to be effective in treating drug-resistant epilepsy, could be a potential adjunct in the treatment of certain GBM cases. Our study aimed to highlight the existing knowledge, identify collaboration networks, and emphasize the ongoing research based on highly cited studies. During the literature search, we found 119 relevant articles written between 2010 and 2023. Among the top 20 most cited articles, there were seven laboratory and five clinical studies. The works of Olson LK, Chang HT, Schwartz KA, and Nikolai M from the Michigan State University, followed by Seyfried TN and Mukherjee P from Boston College, and Olieman JF, and Catsman-Berrevoets CE from the University Medical Center of Rotterdam, were significant contributions. The laboratory studies showed that RKD had a significant antitumor effect and could prolong survival in mouse glioblastoma models. The clinical studies verified the tolerability, efficacy, and safety of RKD in patients with GBM, but raised concerns about whether it could be used as a single therapy. The current research interest is focused on the efficacy of using RKD as an adjunct in selected chemotherapy regimens and demonstrates that it could provide GBM patients with better treatment options. Full article

Nitrogen (N) deposition influences litter decomposition and its water-holding capacity in forest ecosystems. Water conservation remains a priority, so understanding these interactions is vital for managing forests, especially in the Yunnan Plateau region. This study aimed to investigate the effects of simulated N deposition on litter decomposition and water-holding capacity in the Evergreen broad-leaf and Quercus aquifolioides forest in the central Yunnan Plateau. Indoor flooding experiments were performed alongside varied nitrogen deposition treatments. Litter decomposition rates under these treatments were evaluated using the Olson model. In the decomposition study, the N treatments in the Evergreen broad-leaved forest increased the remaining mass by 4.75%–17.50% and 2.09%–16.36% compared with the control (20.97 ± 0.44% and 42.43 ± 0.47%), while in the Quercus aquifolioides forest, the remaining mass of leaves and twigs decreased by 5.00% and 0.70% in the LN treatment compared with the control (35.47 ± 0.39% and 44.10 ± 1.18%) and the MN and HN treatments increased by 2.55%–8.13% and 5.61%–11.28%, respectively. Effects of increased N deposition on litter decomposition changed from promoting to inhibiting, as low N sped up decomposition but higher levels inhibited it. Additionally, N boosted the water-holding capacity of litter, especially in leaves. The litter from both forests displayed a notable ability to absorb water. Nitrogen deposition modulates litter decomposition and water retention properties. Specifically, high nitrogen deposition increases litter water-holding capacity by inhibiting the rate of litter decomposition, which in turn alters its mass remaining rate, lignin, and cellulose remaining rates. Efficient management of the studied forests leveraging nitrogen deposition can boost their water conservation potential, aiding in atmospheric precipitation absorption and surface runoff regulation. Full article

Fenna-Mathews-Olson complexes participate in the photosynthetic process of Sulfur Green Bacteria. These biological subsystems exhibit quantum features which possibly are responsible for their high efficiency; the latter may comprise multipartite entanglement and the apparent tunnelling of the initial quantum state. At first, to study these aspects, a multidisciplinary approach including experimental biology, spectroscopy, physics, and math modelling is required. Then, a global computer modelling analysis is achieved in the computational biology domain. The current work implements the Hierarchical Equations of Motion to numerically solve the open quantum system problem regarding this complex. The time-evolved states obtained with this method are then analysed under several measures of entanglement, some of them already proposed in the literature. However, for the first time, the maximum overlap with respect to the closest separable state is employed. This authentic multipartite entanglement measure provides information on the correlations, not only based on the system bipartitions as in the usual analysis. Our study has led us to note a different view of FMO multipartite entanglement as tiny contributions to the global entanglement suggested by other more basic measurements. Additionally, in another related trend, the initial state, considered as a Förster Resonance Energy Transfer, is tracked using a novel approach, considering how it could be followed under the fidelity measure on all possible permutations of the FMO subsystems through its dynamical evolution by observing the tunnelling in the most probable locations. Both analyses demanded significant computational work, making for a clear example of the complexity required in computational biology. Full article

Quenching and partitioning (QP) steel has attracted much focus due to the effect of phase transformation induced plasticity (TRIP). However, the TRIP behavior makes it difficult to accurately predict the strain and stress distribution as well as the phase transformation behavior of QP steel. Scanning electron microscope (SEM) images of the QP980 microstructure were produced in this study, characterized by a combination of lath martensite, polygonal ferrite and retained austenite. The volume fraction evolution of retained austenite with equivalent plastic strain (EPS) of uniaxial tension was obtained by electron-backscatter diffraction. The phase transformation kinetics equations of QP980 were deduced based on the phase transformation model proposed by Olson and Cohen (simplified as O-C theory), considering the effects of strain rate, deformation temperature and stress state. A constitutive model on the dependence of the phase transformation was proposed to reveal the relation between metallographic characteristics and mechanical performance of QP980 steel during deformation. The User subroutine VUMAT in ABAQUS/Explicit was implemented to describe the volume fraction of retained austenite (VFRA) under different stress states. The established phase transformation and constitutive model were applied to three kinds of complex path loading tests. The variation in the retained austenite under complex strain paths was obtained and compared with the experimental results. Full article

This study proposes a theoretical method to estimate the impact force of Derailment Containment Provisions (DCPs) for the prevention of secondary collisions in the event of a train derailment. By comparing the impact forces estimated using the commonly used Olson model and dynamic simulations, the study identifies significant differences in average and maximum impact forces. The study shows that these differences arise due to the mass effects of vehicle bodies transmitted to the DCP during a collision. To address this issue, the impact force of the Olson model was modified by considering the stiffness of suspensions between masses as a simplified spring–mass model. The modified impact force was verified through impact simulations using the KTX model on curved tracks with various radii. The results show that the modified Olson model provides a reasonable estimate of the impact force, with differences of less than 8% observed under all simulation conditions. This study provides a valuable contribution to the design and analysis methodology for DCPs, improving their effectiveness in preventing secondary collisions and enhancing railway safety. Full article

Suicide is considered a public health problem that affects families worldwide. Family functioning is the capability of the family system to fulfill needs during the stages of its development. In this study, we focused on evaluating family cohesion and adaptability in a group of adolescents who had attempted suicide and were hospitalized at a hospital for mental health disorders, compared to a control group. Methods: based on Olson’s circumplex model, we used the FACES III scale to gain insights into the family functioning of both suicidal and control groups. Results: The case group presented lower scores in cohesion and adaptability compared to the control group, with moderate effect-size for cohesion (Cohen’s d/r test = 1.217/0.52) and low effect-size for adaptability (Cohen’s d/r test = 0.746/0.35) (p < 0.001 for both variables), and also presented predominantly disengaged families (72.5% in the case group vs. 27.5% in the control group) and structured families (45% in the case group vs. 23.8% in the control group). The type of family described by the adolescents with a history of suicide attempts may explain the presence of low self-esteem and little emotional support usually present in this type of patient. Full article

Plant litter decomposition is a key process in the biogeochemical cycles of terrestrial ecosystems. The main goal of this work is to determine the impact of current climate change on the decomposition process of the litter of Palo Laziale Wood (Rome, Italy), one of the last remnants of the Tyrrhenian lowland forest. A time-dependent simulation of leaf litter decay was previously performed on a dynamic semi-empirical model based on Olson’s model (1963). It was also assumed that microbial activity depended on optimal temperature and moisture conditions simulated by Climatic Decomposition Index (CDI). The comparison between the observed and simulated leaf litter biomass reduction over time (t = −0.127, p = 0.901) highlighted the adequacy of CDI in reproducing biomass trends under limiting climatic conditions (high temperature and low precipitation). However, the decomposition model used here was not able to simulate the reduction of recalcitrant compounds (lignin) in strongly limiting conditions of water availability in the Palo Laziale Wood. These climatic conditions were attributable to climate change, which made the year 2020 representative of future years increasingly characterized by limiting climatic conditions. Therefore, it is necessary to carefully calibrate the CDI in order to consider the current and future changes in temperature and water availability in the Mediterranean area, and to, therefore, perform a better model-based foreseeing for leaf litter decomposition. Full article

The main objective of this research is to examine the effects of financial instruments declared under IFRSs on value relevance over thirteen years. The research sample included 35 European enterprises that were listed on the main market of the London Stock Exchange from 2007 to 2019. This study focuses on the adoption of IFRS.7 and IAS.32 disclosure standards, in line with previous studies. The Ohlson model (1995) was utilised in the study to evaluate the dependent variable since it is the module used most often in determining value relevance. The findings indicated that financial knowledge about financial instruments (FI) was typically valuable throughout the research. In addition, the significance of financial instruments and other disclosures when examining sub-components were not valued as relevant but rather provided information regarding the kind and level of exposure to FI risks. Furthermore, the earnings and book value of the common equity have a favourable impact on the value relevance. Hence, the key contributions of this study went beyond enriching the body of literature to make recommendations regarding the most influential determinant among financial instrument items that positively enhance value relevance. Full article