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Optical Trapping for Charge Detection and Spinning
No full textOptical trapping of small particles with laser light is a versatile method for manipulation. In this work two laser trapping experiments are described. In the first experiment the charge of a trapped particle in water is measured with the resolution of the elementary charge, by measuring the displacement in an electric field. An ac electric field is used to exert a sinusoidal force onto the particle, and the amplitude of the oscillation is measured with a quadrant photodetector. This setup has extended the limits of sensitivity, which allows to see discrete steps in the charge of the nanoparticles, even in a highly polar material such as water. In the second experiment micrometer size particles consisting of polymerized chiral liquid crystal start spinning under influence of the polarization of the laser trapping beam. This work consists of experimental results, showing the period of the rotation as a function of the polarization of the laser beam, and simulation results, in which the torque exerted by the laser beam on the chiral particle is calculated. It is observed that some particles can be rotated in both directions when the degree of circular polarization is sufficiently high, while other particles only rotate in one direction.Optical trapping of small particles with laser light is a versatile method for manipulation. In this work two laser trapping experiments are described. In the first experiment the charge of a trapped particle in water is measured with the resolution of the elementary charge, by measuring the displacement in an electric field. An ac electric field is used to exert a sinusoidal force onto the particle, and the amplitude of the oscillation is measured with a quadrant photodetector. This setup has extended the limits of sensitivity, which allows to see discrete steps in the charge of the nanoparticles, even in a highly polar material such as water. In the second experiment micrometer size particles consisting of polymerized chiral liquid crystal start spinning under influence of the polarization of the laser trapping beam. This work consists of experimental results, showing the period of the rotation as a function of the polarization of the laser beam, and simulation results, in which the torque exerted by the laser beam on the chiral particle is calculated. It is observed that some particles can be rotated in both directions when the degree of circular polarization is sufficiently high, while other particles only rotate in one direction.
Scaling up, sustaining, and enhancing school-based sexuality education programs in resource constrained and conservative contexts : replicable lessons from positive-deviant countries
No full textDespite considerable efforts, progress in the implementation of sexuality education (SE) has been uneven. This study identified six "positive-deviant" low- and middle-income countries, i.e., countries that had scaled up, sustained and enhanced their SE programs when many others-in similar social, cultural and economic circumstances-were not able to do so. In other words, they were significantly and consistently more successful than the norm. Countries were shortlisted using a validated framework and were analyzed using three other validated frameworks on political priority setting, scaling up, and stakeholder engagement. The study found that India, Pakistan, Nigeria, Senegal, Mexico, and Uruguay had scaled up (either nationwide or in some states/provinces), sustained and enhanced their SE programs in very different contexts. In all six, SE was a political priority, the national or state/province level SE scale up effort had been carefully planned and managed, and a mix of methods were used to build support and/or to overcome resistance. The study points to what needs to be done better/more energetically/differently in research, program support-tool development, and policy and program support to change the status quo.Despite considerable efforts, progress in the implementation of sexuality education (SE) has been uneven. This study identified six "positive-deviant" low- and middle-income countries, i.e., countries that had scaled up, sustained and enhanced their SE programs when many others-in similar social, cultural and economic circumstances-were not able to do so. In other words, they were significantly and consistently more successful than the norm. Countries were shortlisted using a validated framework and were analyzed using three other validated frameworks on political priority setting, scaling up, and stakeholder engagement. The study found that India, Pakistan, Nigeria, Senegal, Mexico, and Uruguay had scaled up (either nationwide or in some states/provinces), sustained and enhanced their SE programs in very different contexts. In all six, SE was a political priority, the national or state/province level SE scale up effort had been carefully planned and managed, and a mix of methods were used to build support and/or to overcome resistance. The study points to what needs to be done better/more energetically/differently in research, program support-tool development, and policy and program support to change the status quo.A
Dietary species richness provides a comparable marker for better nutrition and health across contexts
No full textEcological diversity indices such as Hill numbers have been developed to estimate effective species numbers, yet the ability of Hill numbers to compare food biodiversity across contexts is unclear. Here we computed the between- and within-country variability of similarity-insensitive Hill numbers using dietary intake collected from prospective cohorts in nine European countries and cross-sectional studies in five low- and middle-income countries. We also assessed the relationships between more biodiverse diets, mortality rates and micronutrient adequacy. Only Hill0, better known as dietary species richness (DSR), showed strong heterogeneity between countries and individuals within countries. Higher DSR was most strongly associated with lower mortality rates in Europe as compared to Hill1, Hill2 and Hill∞, whereas relationships with micronutrient adequacy were comparable across Hill numbers in the global south. DSR can be used to assess progress towards more biodiverse diets, while also serving as a marker for the deleterious nutrition and health impacts associated with non-diverse diets.Ecological diversity indices such as Hill numbers have been developed to estimate effective species numbers, yet the ability of Hill numbers to compare food biodiversity across contexts is unclear. Here we computed the between- and within-country variability of similarity-insensitive Hill numbers using dietary intake collected from prospective cohorts in nine European countries and cross-sectional studies in five low- and middle-income countries. We also assessed the relationships between more biodiverse diets, mortality rates and micronutrient adequacy. Only Hill0, better known as dietary species richness (DSR), showed strong heterogeneity between countries and individuals within countries. Higher DSR was most strongly associated with lower mortality rates in Europe as compared to Hill1, Hill2 and Hill∞, whereas relationships with micronutrient adequacy were comparable across Hill numbers in the global south. DSR can be used to assess progress towards more biodiverse diets, while also serving as a marker for the deleterious nutrition and health impacts associated with non-diverse diets.A
Bio-polyol chemical design for self-healing boronate ester gels by green oxyalkylation of organosolv lignin
No full textLignin, the most abundant aromatic biopolymer, has a high potential as an alternative to fossil resources in the chemical industry. However, the non-uniformity of lignin is currently a drawback for high-end applications. In this work, glycerol carbonate being a green and safe cyclic carbonate was therefore applied in the oxyalkylation of organosolv lignin (weight average molecular weight of approximate to 8,300 g mol-1; aliphatic OH content of ca. 2.61 mmol g- 1) to obtain a lignin-based polyol with solely aliphatic OH functionalities. The catalyst type, reaction temperature and time and additional solvents were evaluated in the oxyalkylation with optimal settings using K2CO3, 175 degrees C, 30 min reaction time without any additional solvent to make a modified lignin with a weight average molecular weight of ca. 15,000 g mol-1 and an aliphatic OH content of ca. 4.59 mmol g- 1. To support mechanistic understanding it is shown that the carboxylic acid and phenolic hydroxyl functionalities are converted completely into 1,2-diols, while native aliphatic OH functionalities take at most slightly part in the modification reaction. Furthermore, upon the formation of vicinal diols, the functionalities partially react with glycerol carbonate by an internal transesterification into cyclic carbonate functionalities, this undesirable reaction being more dominant at lower temperatures. Notably, the performance of the oxyalkylation strategy is sufficient to crosslink the modified lignin with benzene-1,4-diboronic acid into a gel-like material with identical shear storage and loss moduli before destruction and immediately after destruction (for the lowest amount of crosslinker added = 1:1.15 diol/boronic acid functionalities molar ratio).Lignin, the most abundant aromatic biopolymer, has a high potential as an alternative to fossil resources in the chemical industry. However, the non-uniformity of lignin is currently a drawback for high-end applications. In this work, glycerol carbonate being a green and safe cyclic carbonate was therefore applied in the oxyalkylation of organosolv lignin (weight average molecular weight of approximate to 8,300 g mol-1; aliphatic OH content of ca. 2.61 mmol g- 1) to obtain a lignin-based polyol with solely aliphatic OH functionalities. The catalyst type, reaction temperature and time and additional solvents were evaluated in the oxyalkylation with optimal settings using K2CO3, 175 degrees C, 30 min reaction time without any additional solvent to make a modified lignin with a weight average molecular weight of ca. 15,000 g mol-1 and an aliphatic OH content of ca. 4.59 mmol g- 1. To support mechanistic understanding it is shown that the carboxylic acid and phenolic hydroxyl functionalities are converted completely into 1,2-diols, while native aliphatic OH functionalities take at most slightly part in the modification reaction. Furthermore, upon the formation of vicinal diols, the functionalities partially react with glycerol carbonate by an internal transesterification into cyclic carbonate functionalities, this undesirable reaction being more dominant at lower temperatures. Notably, the performance of the oxyalkylation strategy is sufficient to crosslink the modified lignin with benzene-1,4-diboronic acid into a gel-like material with identical shear storage and loss moduli before destruction and immediately after destruction (for the lowest amount of crosslinker added = 1:1.15 diol/boronic acid functionalities molar ratio).A
A qualitative study on the factors influencing oral health care for young children in Belgium
No full textBackgroundDental caries in young children is a severe public health problem. Children depend on their parents and care professionals for their oral health. The aim of this study is to gain in-depth insight into the factors influencing oral health care for young children.MethodsA qualitative explorative research design, within a constructivist research paradigm, was used. Eight individual and three focus group interviews were conducted with parents of children aged 6 months to 6 years. Particular emphasis was dedicated to the inclusion of parents from minority groups. Individual interviews were conducted with eight professionals from different health and welfare sectors working with young children and families. Data were analysed using reflexive thematic analysis.ResultsSeveral factors influence young children's oral health, including time issues, children's uncooperative behaviour, parents' own oral health habits, family and cultural norms, and lack of knowledge. Parents from minority groups experience more barriers. Non-dental professionals report different barriers for taking responsibility about the topic including lack of time, lack of knowledge, and considering oral health as a taboo subject.ConclusionCare guidelines for young children and training in initiating conversations regarding oral health with parents are needed for professionals.BackgroundDental caries in young children is a severe public health problem. Children depend on their parents and care professionals for their oral health. The aim of this study is to gain in-depth insight into the factors influencing oral health care for young children.MethodsA qualitative explorative research design, within a constructivist research paradigm, was used. Eight individual and three focus group interviews were conducted with parents of children aged 6 months to 6 years. Particular emphasis was dedicated to the inclusion of parents from minority groups. Individual interviews were conducted with eight professionals from different health and welfare sectors working with young children and families. Data were analysed using reflexive thematic analysis.ResultsSeveral factors influence young children's oral health, including time issues, children's uncooperative behaviour, parents' own oral health habits, family and cultural norms, and lack of knowledge. Parents from minority groups experience more barriers. Non-dental professionals report different barriers for taking responsibility about the topic including lack of time, lack of knowledge, and considering oral health as a taboo subject.ConclusionCare guidelines for young children and training in initiating conversations regarding oral health with parents are needed for professionals.A
Arbitrability of PPP contract disputes in China : based on an analysis of 68 Chinese cases
No full textThe ongoing debate centers on the question of whether disputes arising from PPP contracts can be arbitrated, which has theoretical and practical implications. The theoretical discourse is primarily concerned with the legal nature of PPP contracts and the merits underlying their disputes. Legislative inconsistencies exist surrounding the legal nature of these contracts and their dispute resolution method. Based on an examination of 68 relevant cases in Chinese courts, the judiciary remains skeptical about the feasibility of arbitration. In light of these, this research will address the intricate relationship between the legal nature of PPP contracts and the merits embedded in disputes that contribute to their arbitrability. It contends that the arbitrability of PPP disputes is contingent on the merits of the dispute rather than the legal nature of the contract. By conducting a comprehensive reevaluation of legal rules regarding the arbitrability of PPP contract disputes, it seeks to provide clarity by distinguishing PPP agreements from administrative agreements, while also emphasizing that arbitration of PPP agreement disputes is not expressly prohibited. Drawing on the "proximate cause theory" in English Contract Law, the use of administrative authority within the legal relationships of conflicts is identified, thereby distinguishing the substantive differences between administrative and civil legal disputes within PPP contracts. Finally, the study aims to chart a course for the arbitrability of PPP contract disputes.The ongoing debate centers on the question of whether disputes arising from PPP contracts can be arbitrated, which has theoretical and practical implications. The theoretical discourse is primarily concerned with the legal nature of PPP contracts and the merits underlying their disputes. Legislative inconsistencies exist surrounding the legal nature of these contracts and their dispute resolution method. Based on an examination of 68 relevant cases in Chinese courts, the judiciary remains skeptical about the feasibility of arbitration. In light of these, this research will address the intricate relationship between the legal nature of PPP contracts and the merits embedded in disputes that contribute to their arbitrability. It contends that the arbitrability of PPP disputes is contingent on the merits of the dispute rather than the legal nature of the contract. By conducting a comprehensive reevaluation of legal rules regarding the arbitrability of PPP contract disputes, it seeks to provide clarity by distinguishing PPP agreements from administrative agreements, while also emphasizing that arbitration of PPP agreement disputes is not expressly prohibited. Drawing on the "proximate cause theory" in English Contract Law, the use of administrative authority within the legal relationships of conflicts is identified, thereby distinguishing the substantive differences between administrative and civil legal disputes within PPP contracts. Finally, the study aims to chart a course for the arbitrability of PPP contract disputes.A
A new thermoelastic model for agglomerated and randomly-oriented CNT-reinforced bio-inspired materials: Temperature-dependent free vibration analysis of FG-CNTR-TPMS plates
No full textA new thermoelastic model is introduced to reveal equivalent mechanical and thermal properties of randomly oriented (RO), agglomerated carbon nanotube (CNT) inclusions within a matrix material. Thereafter, a bioinspired FG-CNTR-TPMS material model is established through three typical triply periodic minimal surfaces (TPMS) microstructures reinforced with CNTs and functionally graded (FG) schemes. The free vibration behavior of macro-scale plates made from FG-CNTR-TPMS materials under thermal effects and material temperature dependencies is then devised. A new higher-order shear deformation (HSDT) five-variable plate theory incorporated with isogeometric analysis (IGA) is proposed to show its reliability and efficiency. Various material conditions have been thoroughly studied, emphasizing the influence of CNT reinforcement states and environment temperatures. While increasing the CNT volume fraction (fr) greatly improves the plate frequencies, the temperature rise (Delta T) leads to an opposite influence. These properties can amplify or weaken the effects of porosity distributions on the plate's natural frequencies both beneficial and unfavorable aspects. Notably, the outstanding elastic modulus of IWP-type TPMS enlarges the initial thermal stress and ratio between mechanical and thermal stiffness, causing greater impacts on plate behaviors in the thermal environment. In some exceptional cases, FG-CNTR-TPMS plates with P-type can exceed isotropic plates in stiffness-to-weight ratios, which is an extraordinary characteristic of porous structures. In various scenarios of CNT agglomeration, this natural phenomenon shows noticeable reductions in plate frequencies up to 40% when considering temperature changes. Bridging the gap between TPMS-based lattice structures and CNTreinforced composites, this study contributes to advancing the knowledge of advanced bio-inspired materials. The findings from this work can revolutionize their potential applications in various engineering areas, particularly biomedical devices, energy storage, flexible electronics, advanced textiles, and soft robotics, where lightweight, high-strength, and temperature-resistant structural components are critical.A new thermoelastic model is introduced to reveal equivalent mechanical and thermal properties of randomly oriented (RO), agglomerated carbon nanotube (CNT) inclusions within a matrix material. Thereafter, a bioinspired FG-CNTR-TPMS material model is established through three typical triply periodic minimal surfaces (TPMS) microstructures reinforced with CNTs and functionally graded (FG) schemes. The free vibration behavior of macro-scale plates made from FG-CNTR-TPMS materials under thermal effects and material temperature dependencies is then devised. A new higher-order shear deformation (HSDT) five-variable plate theory incorporated with isogeometric analysis (IGA) is proposed to show its reliability and efficiency. Various material conditions have been thoroughly studied, emphasizing the influence of CNT reinforcement states and environment temperatures. While increasing the CNT volume fraction (fr) greatly improves the plate frequencies, the temperature rise (Delta T) leads to an opposite influence. These properties can amplify or weaken the effects of porosity distributions on the plate's natural frequencies both beneficial and unfavorable aspects. Notably, the outstanding elastic modulus of IWP-type TPMS enlarges the initial thermal stress and ratio between mechanical and thermal stiffness, causing greater impacts on plate behaviors in the thermal environment. In some exceptional cases, FG-CNTR-TPMS plates with P-type can exceed isotropic plates in stiffness-to-weight ratios, which is an extraordinary characteristic of porous structures. In various scenarios of CNT agglomeration, this natural phenomenon shows noticeable reductions in plate frequencies up to 40% when considering temperature changes. Bridging the gap between TPMS-based lattice structures and CNTreinforced composites, this study contributes to advancing the knowledge of advanced bio-inspired materials. The findings from this work can revolutionize their potential applications in various engineering areas, particularly biomedical devices, energy storage, flexible electronics, advanced textiles, and soft robotics, where lightweight, high-strength, and temperature-resistant structural components are critical.A
Utility maximization and change of variable formulas for time-changed dynamics
No full textIn this paper we derive novel change of variable formulas for stochastic integrals w.r.t. a time-changed Brownian motion where we assume that the time-change is a general increasing stochastic process with finitely many jumps in a bounded set of the positive half-line and is independent of the Brownian motion. As an application we consider the problem of maximizing the expected utility of the terminal wealth in a semimartingale setting, where the semimartingale is written in terms of a time-changed Brownian motion and a finite variation process. To solve this problem, we use an initial enlargement of filtration and our change of variable formulas to shift the problem to a maximization problem under the enlarged filtration for models driven by a Brownian motion and a finite variation process. The latter problem can be solved by using martingale properties. Then applying again a change of variable formula, we derive the optimal strategy for the original problem for a power utility and for a logarithmic utility.In this paper we derive novel change of variable formulas for stochastic integrals w.r.t. a time-changed Brownian motion where we assume that the time-change is a general increasing stochastic process with finitely many jumps in a bounded set of the positive half-line and is independent of the Brownian motion. As an application we consider the problem of maximizing the expected utility of the terminal wealth in a semimartingale setting, where the semimartingale is written in terms of a time-changed Brownian motion and a finite variation process. To solve this problem, we use an initial enlargement of filtration and our change of variable formulas to shift the problem to a maximization problem under the enlarged filtration for models driven by a Brownian motion and a finite variation process. The latter problem can be solved by using martingale properties. Then applying again a change of variable formula, we derive the optimal strategy for the original problem for a power utility and for a logarithmic utility.A
Early and Middle Holocene climate and environmental change
No full textThe Mesolithic corresponds to a period of abrupt global warming resulting in a series of profound environmental changes, such as rapid sea level rise, decreased river discharge and lake levels, increased drought and forest fires, and a radical overturn of both fauna and flora. The latter includes the rapid replacement of cold-tolerant species occurring in an open tundra environment by temperate-boreal species, adapted to the forested environment of the Early and Middle Holocene. However, global warming was repeatedly interrupted by short but abrupt cooling events, the impact of which on both ecosystems and humans remains largely unexplored.The Mesolithic corresponds to a period of abrupt global warming resulting in a series of profound environmental changes, such as rapid sea level rise, decreased river discharge and lake levels, increased drought and forest fires, and a radical overturn of both fauna and flora. The latter includes the rapid replacement of cold-tolerant species occurring in an open tundra environment by temperate-boreal species, adapted to the forested environment of the Early and Middle Holocene. However, global warming was repeatedly interrupted by short but abrupt cooling events, the impact of which on both ecosystems and humans remains largely unexplored.B
