Top-down Strategy Research Articles

Urea/Thiourea Imine Linkages Provide Accessible Holes in Flexible Covalent Organic Frameworks and Dominates Self-Adaptivity and Exciton Dissociation.

Unraveling the robust self-adaptivity and minimal energy-dissipation of soft reticular materials for environmental catalysis presents a compelling yet unexplored avenue. Herein, a top-down strategy, tailoring from the unique linkage basis, flexibility degree, skeleton electronics to trace-guest adaptability, is proposed to fill the understanding gap between micro-soft covalent organic frameworks (COFs) and photocatalytic performance. The thio(urea)-basis-dominated linkage within benzotrithiophene-based COFs induce the framework contraction/swelling (intralayer micro-flexibility) in response to tetrahydrofuran or water. Adaptability of micro-flexible thiourea-COF with pore hydrophilicity not only contributes to the favorable mass transfer, but also enhances the accessible redox active sites, culminating in nearly 100% removal of micropollutant with low-energy dissipation in wastewater. The incorporating urea/thiourea into imine linkage facilitates polarization reduction and exciton dissociation within skeleton wall, inducing strong localization for holes. This transformation facilitates interchain charge transport and unbalanced distribution conducive to oxidative holes-mediated micropollutant decomposition.

Task-switching mechanisms under methamphetamine cravings: sex differences in cued and voluntary task-switching

IntroductionThis study explored the effects of task-switching type and sex on the task-switching ability of methamphetamine abstainers, as well as the differences in brain mechanisms under drug cravings under drug cravings using near-infrared spectroscopy.MethodsCraving-inducing videos were used to arouse 20 methamphetamine abstainers (including 10 men), whose switching ability was then assessed using voluntary and cued task-switching exercises.ResultsDuring task-switching under methamphetamine cravings, the activation of the premotor cortex (PMC), supplementary motor area (SMA), frontal eye field (FEF), and dorsolateral prefrontal cortex (DLPFC) in women was significantly stronger than in men, while the activation of FEF in men was significantly stronger than in women. Voluntary task-switching induced stronger FEF activation than cued task-switching. During the latter, women exhibited stronger activation in the anterior prefrontal cortex (aPFC) than men.DiscussionBoth men and women showed brain lateralization during task-switching under methamphetamine cravings. Men tended to adopt proactive control and use a top-down dominant strategy to start a new task. Women, however, tend to use a bottom-up strategy focusing on inhibiting old tasks and emotional switching. Moreover, in cued task-switching, the result shows women paid more attention to emotional processing than did men, which suggests that different task-switching training programs should be developed according to sex.

Influence of different sample preparation approaches on proteoform identification by top-down proteomics.

Top-down proteomics using mass spectrometry facilitates the identification of intact proteoforms, that is, all molecular forms of proteins. Multiple past advances have lead to the development of numerous sample preparation workflows. Here we systematically investigated the influence of different sample preparation steps on proteoform and protein identifications, including cell lysis, reduction and alkylation, proteoform enrichment, purification and fractionation. We found that all steps in sample preparation influence the subset of proteoforms identified (for example, their number, confidence, physicochemical properties and artificially generated modifications). The various sample preparation strategies resulted in complementary identifications, substantially increasing the proteome coverage. Overall, we identified 13,975 proteoforms from 2,720 proteins of human Caco-2 cells. The results presented can serve as suggestions for designing and adapting top-down proteomics sample preparation strategies to particular research questions. Moreover, we expect that the sampling bias and modifications identified at the intact protein level will also be useful in improving bottom-up proteomics approaches.

Exploring the Relationship between Top-Down and Bottom-Up Strategies in Listening

Exploring the Relationship between Top-Down and Bottom-Up Strategies in Listening

Enhancing the effectiveness of heat adaptation strategies through citizen science-based outdoor thermal comfort

Urbanization and intensifying climate change expose populations in cities to escalating heat stress and associated health risks. Mitigating these challenges require comprehensive assessments that combine quantitative and qualitative data to develop effective heat wave response strategies and policies. Previous research has primarily focused on thermal sensation measured by individual biometrics within specific locations. However, limitations in data collection across large areas often lead to the neglect of the influence of diverse urban environments. This may disregard the importance of regional variations and citizen engagement in formulating effective heat wave mitigation strategies. This study explored the impact of heat wave frequency and intensity across various urban spatial types and assessed thermal sensation vote (TSV) among residents of Suwon City using a citizen science approach. Temperature measurements and subjective heat sensations were collected over a three-year period using homemade temperature sensors. The analysis investigated thermal sensation differences across spatial types—open high rise, open low rise, compact mid-rise, urban park, and lake park—utilizing boxplots, and examined TSV variations by age using the R program localized smoothing methodology. Results indicate significant variations in TSV across different urban areas, particularly when temperatures exceeded 32 °C. The TSV was highest in the lake park areas (average thermal sensation vote +3.5) and was comparatively lower in the open high-rise and open low-rise areas (average thermal sensation vote +2.0). A significant age-related trend was observed, with the highest TSV reported by the 19–30 age group. Heat sensitivity appeared to decrease among participants aged 41 and over. These findings highlight the limitations of traditional top-down heatwave response strategies, which may not adequately account for spatial variations and individual experiences. Conversely, a bottom-up approach that leverages citizen science can inform the development of tailored and proactive strategies that consider a region's specific conditions.

Porous silicon/carbon composites as anodes for high-performance lithium-ion batteries

Silicon anodes are promising for use in lithium-ion batteries. However, their practical application is severely limited by their large volume expansion leading to irreversible material fracture and electrical disconnects. This study proposes a new top-down strategy for preparing microsize porous silicon and introduces polyacrylonitrile (PAN) for a nitrogen-doped carbon coating, which is designed to maintain the internal pore volume and lower the expansion of the anode during lithiation and delithiation. We then explore the effect of temperature on the evolution of the structure of PAN and the electrochemical behavior of the composite electrode. After treatment at 400 -, the PAN coating retains a high nitrogen content of 11.35%, confirming the presence of C―N and C―O bonds that improve the ionic-electronic transport properties. This treatment not only results in a more intact carbon layer structure, but also introduces carbon defects, and produces a material that has remarkable stable cycling even at high rates. When cycled at 4 A g−1, the anode had a specific capacity of 857.6 mAh g−1 even after 200 cycles, demonstrating great potential for high-capacity energy storage applications.

An Overview of Transdisciplinary and Bottom-up Approach for Urban Resilience: The Case of Turkey

While top-down strategies have traditionally dominated urban planning in Turkey, recent shifts towards participatory practices and project-based policies have aimed to involve citizens in decision-making processes. Nevertheless, in the case of Turkey, these participatory models are inadequate for effectively addressing resilience. This article therefore discusses the role of participatory processes in creating resilient cities, as well as how to strengthen transdisciplinary (TR) and bottom-up approaches to urban participation in Turkish urban contexts. The article presents a theoretical framework that connects TR and bottom-up approaches based on existing literature, practices, and planning policy examples. It argues that TR approaches complement bottom-up approaches to urban governance by enhancing urban and social resilience, strengthening local communities, and reducing urban inequalities. Urban planning efforts that promote collaboration, incorporate multiple perspectives, and involve local communities in decision-making processes can address complex urban issues while also fostering long-term sustainability and resilience. This approach not only instills a sense of ownership and empowerment among urban residents but also leverages knowledge and skills to generate more effective and sustainable solutions. By creating a framework that promotes long-term education and citizenship awareness, urban governance can sustain urban resilience in a more viable manner over the long term in Turkey.

Evaluating the Robustness of Transfer Learning with Recipes on Small Data– Using Data of Birds as an Example

Processing small data in machine learning often leads to challenges like low accuracy and overfitting. To address these issues effectively, it is essential to assess the integrity of the underlying problem. One effective approach to tackling such challenges is to adopt a top-down strategy, focusing on adjusting and creating a suitable framework. In this paper, various techniques will be employed to fine-tune the model for optimization. Experiments will be conducted on six distinct datasets to enhance the model’s accuracy and prevent overfitting.

Engineering Microbial Consortia as Living Materials: Advances and Prospectives.

The field of Engineered Living Materials (ELMs) integrates engineered living organisms into natural biomaterials to achieve diverse objectives. Multiorganism consortia, prevalent in both naturally occurring and synthetic microbial cultures, exhibit complex functionalities and interrelationships, extending the scope of what can be achieved with individual engineered bacterial strains. However, the ELMs comprising microbial consortia are still in the developmental stage. In this Review, we introduce two strategies for designing ELMs constituted of microbial consortia: a top-down strategy, which involves characterizing microbial interactions and mimicking and reconstructing natural ecosystems, and a bottom-up strategy, which entails the rational design of synthetic consortia and their assembly with material substrates to achieve user-defined functions. Next, we summarize technologies from synthetic biology that facilitate the efficient engineering of microbial consortia for performing tasks more complex than those that can be done with single bacterial strains. Finally, we discuss essential challenges and future perspectives for microbial consortia-based ELMs.

Bottom-up construction of defective TiO2 microspheres with hierarchical architectures and controlled crystallites for visible-light photocatalysis

Defect-engineering of TiO2 materials has emerged as an effective strategy to enhance the light adsorption and improve the photocatalytic activity under visible-light. However, the designing and fabricating of hierarchically structured TiO2 with controllable crystalline phases and stable structure defects is challenging and rarely reported. Herein, we present a novel bottom-up synthesis strategy to prepare defective TiO2 microspheres with hierarchical architecture and abundant phase junctions. The phase composition and defect concentration of the obtained TiO2 can be easily adjusted by regulating the amount of urea. Moreover, the formation mechanism of hierarchical defective TiO2 microspheres has been investigated. Notably, compared with the defective TiO2 prepared with traditional top-down strategies, more bulk Ti3+ and oxygen vacancies can be generated, which is crucial for the stability of materials. Such integration of unique hierarchical architecture, stable structure defects as well as abundant anatase/rutile phase junctions not only result in the narrowed band gap and improved visible-light absorption, but also allow the fast interfacial electron transfer and better charge separation, leading to enhanced photocatalytic activities in RhB degradation and hydrogen generation under visible light (λ>400 nm) irradiation.

Public Perception of the Food Estate Program of Cassava Cultivation as a Strategic Logistic Reserve in Realizing Regional Food Security in Gunung Mas Regency, Central Kalimantan

This research examines the implementation challenges of Indonesia’s Strategic Logistics Reserve Development Program (CLS), specifically focusing on cassava cultivation in Gunung Mas Regency. Launched as part of the 2020-2024 National Strategic Program (PSN), the initiative aims to address potential food security issues exacerbated by the COVID-19 pandemic, land degradation, and climate change. The program's primary goal is to develop food estates to enhance national food security. The study employs a mixed-methods approach, including interviews with key stakeholders, analysis of program documentation, and community surveys to assess the program’s effectiveness and impact. Key findings reveal significant obstacles, including policy misalignment, unsuitable land conditions for cassava, inadequate infrastructure, and a top-down implementation strategy that lacks local community involvement. Results indicate that while the program has led to some positive outcomes, such as job creation and increased food independence, it has also faced severe criticism. Issues such as suboptimal cassava growth, environmental damage, and socio-cultural impacts have led to negative public perceptions. The failure to issue a crucial Presidential Decree, poor inter-governmental coordination, and inadequate understanding of the program by local communities have compounded these challenges. Analysis suggests that the program’s shortcomings are due to a combination of regulatory delays, environmental mismatches, and insufficient stakeholder engagement. To address these issues, the research recommends a comprehensive evaluation of the program, restoration of damaged lands, enhanced community participation, and stronger environmental safeguards. Improved collaboration between central and regional governments and better alignment of policies and infrastructure are essential for the program’s success in achieving its food security objectives.

Distinct neural pathway and its information flow for blind individual's Braille reading

Natural Braille reading presents significant challenges to the brain networks of late blind individuals, yet its underlying neural mechanisms remain largely unexplored. Using natural Braille texts in behavioral assessments and functional MRI, we sought to pinpoint the neural pathway and information flow crucial for Braille reading performance in late blind individuals. In the resting state, we discovered a unique neural connection between the higher-order ‘visual’ cortex, the lateral occipital cortex (LOC), and the inferior frontal cortex (IFC) in late blind individuals, but not in sighted controls. The left-lateralized LOC-IFC connectivity was correlated with individual Braille reading proficiency. Prolonged Braille reading practice led to increased strength of this connectivity. During a natural Braille reading task, bidirectional information flow between the LOC and the IFC was positively modulated, with a predominantly stronger top-down modulation from the IFC to the LOC. This stronger top-down modulation contributed to higher Braille reading proficiency. We thus proposed a two-predictor multiple regression model to predict individual Braille reading proficiency, incorporating both static connectivity and dynamic top-down communication between the LOC-IFC link. This work highlights the dual contributions of the occipito-frontal neural pathway and top-down cognitive strategy to superior natural Braille reading performance, offering guidance for training late blind individuals.

PROPOSAL FOR AN EMBRYONIC MODEL TO PROMOTE SMART CITIES, IMPLEMENTED IN A BOTTOM-UP FORMAT, APPLIED TO THE AMAZON REGION

Environmental changes, many of which result from human negligence, have driven managers to adopt sustainable practices that adhere to the concept of Smart Cities, a concept that is becoming popular among administrators of Brazilian metropolises. This movement has been corroborated by ABNT standards and the federal government. However, in less developed regions such as Northern Brazil, where challenges are greater and resources are limited, traditional top-down urban development strategies such as BRTs have proven inefficient as initial solutions. This article investigates the feasibility of implementing projects for Smart Cities in the Amazon region given the scarcity of resources. It proposes an alternative bottom-up model titled Smart Launch, which is shown to be more viable for sustainable development in regions with these characteristics. The model recommends starting with smaller and more manageable projects that can be easily implemented without extensive bureaucracy or significant investments. Once established, the model can be quickly replicated and adapted in other locations. The case of the UsiPaz (Peace Plants) in Pará exemplifies the success of this approach and has been taken as a case study, showing significant reduction in violence rates and an increase in the sense of community belonging, as evidenced by qualitative research through semi-structured interviews with managers from three plants in different neighborhoods of the metropolitan region of Belém.

An analytic traction-displacement model for a reinforcing ligament bridging a crack at an arbitrary angle, including elastic, frictional, snubbing, yielding, creep, and fatigue phenomena

A micromechanical model is developed that generates analytic expressions for the crack displacement vector u given an arbitrary far-field stress state σa for a crack that is bridged by an array of ligaments oriented at an arbitrary angle with respect to the crack plane. The model is applicable to various materials, e.g., fibrous ceramic composites, or polymer composites reinforced by stitches or z-pins or woven tows, and deals with interfacial friction, enhanced friction due to increased contact pressure (“snubbing”), and the possibility of ligament deflection enabled by yield or damage. The model also conveniently incorporates ligament failure and rate dependent phenomena (fatigue or creep). Adaptability of the model is enabled by the definition of a standard Reference Model, which generates analytic expressions for the crack displacement for given possible yield, ligament deflection, and friction and snubbing effects and is invariant for all geometrical and material choices. The switching on or off and the strengths of all phenomena are governed by assigning values to a handful of material parameters. The material parameters will generally be calibrated against data in a top-down strategy, the model thereby mapping material selection onto engineering fracture via the predicted bridging relationship u[σa]. The relationship u[σa] can depend strongly on bi-angular ligament orientation. Yield and deflection can change u[σa] qualitatively, e.g., by creating fracture surface contact even when σa includes substantial opening tension. Snubbing has significant effects, including possible stabilization of the pullout of a finite ligament. Since model output is computed via analytic expressions, its speed will support the model's use in large-scale material simulations or as constraining physical information in machine learning algorithms.

Human relevance of in vivo and in vitro skin irritation tests for hazard classification of pesticides

Background: Test methods to inform hazard characterization and labeling of pesticides to protect human health are typically conducted using laboratory animals, and for skin irritation/corrosion the rabbit Draize test is currently required by many regulatory agencies. Although the Draize test is generally regarded to provide protective classifications for human health, new approach methodologies (NAMs) have been developed that offer more human relevant models that circumvent the uncertainty associated with species differences that exist between rabbits and humans. Despite wide applicability and use of these test methods across a broad range of chemicals, they have not been widely adopted for testing pesticides and pesticidal formulations. One of the barriers to adoption of these methods in this sector is low concordance with results from the Draize rabbit test, particularly for chemicals within the mild to moderate irritation spectrum. Methods: This review compares and contrasts the extent to which available models used in skin irritation testing mimic the anatomy and physiology of human skin, and how each aligns with the known key events leading to chemically-induced adverse skin irritation and corrosion. Doing so fully characterizes the human relevance of each method. Results: As alternatives to the rabbit Draize test, several protocols using ex vivo, in chemico, and in vitro skin models are available as internationally harmonized test guidelines. These methods rely on a variety of models of human skin, including excised rodent skin, synthetic biochemical models of barrier function, cell culture systems, and reconstructed human tissue models. We find these models exhibit biological and mechanistic relevance aligned with human skin irritation responses. Further, recent retrospective analyses have shown that the reproducibility of the Draize test is less than 50% for mild and moderate responses, with many of the replicate predictions spanning more than one category (e.g., a moderate response reported in one study followed by a non-irritant response reported in another study). Conclusions: Based on this comparative evaluation, we recommend top-down and bottom-up testing strategies that use the most human relevant in vitro test methods for skin irritation and corrosion classification of pesticides and pesticide formulations. To further discriminate among mild and non-irritant formulations, optimization of a cytokine release protocol and subsequent analyses of reference formulation test results is recommended.

China’s digital and green (twin) transition: insights from national and regional innovation policies

ABSTRACT This paper examines the role of policy in China’s digital and green (twin) transition, building on a qualitative study of a large corpus of policy documents in green and digital domains. We analyse the multi-level governance of these transitions for three regional case studies: Shanghai, Wuhan and Hangzhou. We find that regions both adopt and adjust green and digital aims and means differently from national policy. A twin transition is not comprehensively addressed at the national level, but is partially implemented in the three regions. Based on our findings, we develop a regional typology sketching top-down policy implementation strategies.

Carbon Quantum Dot-Functionalized Dermis-Derived Transparent Electronic Skin for Multimodal Human Motion Signal Monitoring and Construction of Self-Powered Triboelectric Nanogenerator.

Electronic skin (e-skin) is considered as a highly promising interface for human-computer interaction systems and wearable electronic devices. Through elaborate design and assembly of various materials, it possesses multiple characteristics similar to human skin, including remarkable flexibility, stretchability, sensitivity to temperature and humidity, biocompatibility, and efficient interfacial ion/electron transport capabilities. Here, we innovatively integrate multifunctional carbon quantum dots (CQDs), which exhibit conductivity, antibacterial properties, ultraviolet absorption, and fluorescence emission, with poly(acrylic acid) and glycerin (Gly) into a three-dimensional network structure of natural goatskin collagen fibers. Through a top-down design strategy enhanced by hydrogen bond reconstruction, we successfully fabricated a novel transparent e-skin (PAC-eSkin). This e-skin exhibited significant tensile properties (4.94 MPa of tensile strength and 263.42% of a maximum breaking elongation), while also possessing Young's modulus similar to human skin (2.32 MPa). It is noteworthy that the functionalized CQDs used was derived from discarded goat hair, and the addition of Gly gave PAC-eSkin excellent antifreezing and moisturizing properties. Due to the presence of ultrasmall CQDs, which creates efficient ion/electron transport channels within PAC-eSkin, it could rapidly sense human motion and physiological signals (with a gauge factor (GF) of 1.88). Furthermore, PAC-eSkin had the potential to replace traditional electrode patches for real-time monitoring of electrocardiogram, electromyogram, and electrooculogram signals, with a higher SNR (signal-to-noise ratio) of 25.1 dB. Additionally, the customizable size and shape of PAC-eSkin offer vast possibilities for the construction of single-electrode triboelectric nanogenerator systems. We have reason to believe that the design and development of this transparent e-skin based on CQDs-functionalized dermal collagen matrices can pave a new way for innovations in human-computer interaction interfaces and their sensing application in diverse scenarios.

Towards growth-driven environmentalism: The green energy transition and local state in China

China is recognised as the leading country in the green energy transition. Different from the literature that emphasises the role of the powerful central state, this article reveals how China's green energy strategies and policies can also be reshaped by local dynamics. Based on ethnographic research in 2022 and interviews with local officials and villagers, this article interrogates the building of ‘the world's largest desert photovoltaic (PV) power base’ in Dalad, an Inner Mongolian county in northwest China. The article makes two arguments. First, the base project should be seen as a product of what I term ‘growth-driven environmentalism’, which characterises the local state's mediation between the top-down energy strategies and the bottom-up developmental needs. Second, while the base project may be viewed as a successful climate action in its own right, it obscures the concurrent acceleration of coal-based industrial growth and entrenches the energy-based development model in Dalad. This article offers a theoretical contribution to our understanding of the role of the local state in reconstructing and reshaping the green energy transition, alongside the powerful central state, and suggests that understandings of the global green energy transition must step past the macro picture to understand what is on the ground.

Spillover effects of structure-adjustment pollution reduction measures in China's iron and steel industry

The iron and steel industry (ISI) is a significant source of sulfur dioxide and particulate matter pollution in China. Existing research on regional environmental regulation or ISI emission reduction strategies tends to overlook spillover effects and the enterprise perspective. During the heating season, production limitations in ISI are potential policy measures for achieving structural emission reductions in heavily polluted cities in China's Jing-Jin-Ji and surrounding regions. We adopt a bottom-up modeling approach, incorporating effective production time to describe enterprise behavior and establishing a quantitative trade model based on trade theory. By modeling three types of production restriction policies outlined in policy documents, we evaluate the emission reduction effects of structure-adjustment measures using the example of reduced effective production time for steel-producing enterprises in the air pollution transmission channel in the Beijing-Tianjin-Hebei area. The results indicate the following: (1) Reducing the effective production time of ISI enterprises can help decrease domestic production value and total factor productivity in pollution-intensive industries, including but not limited to ISI. It also leads to reduced emissions of various pollutants in the implementation regions. (2) Due to interprovincial trade and input-output linkages, structural reduction measures in certain regions have implications for almost all other provinces' industrial structures. Differences in initial industrial structures, factor endowments, and geographical locations contribute to varying directions and magnitudes of industrial structural changes. Pollution-intensive industries' share tends to increase higher in less developed regions. (3) Our estimated pollution reduction is smaller compared to the literature evaluating clean air policies in similar regions using top-down strategies. This discrepancy arises because we analyze a single policy tool rather than modeling industry-wide emission fluctuations from the top down. Additionally, our modeling approach allows us to examine dynamic changes in comparative advantages. The increase in production scale for certain industries in policy-affected regions partially offsets the decline in pollution emissions. These findings enhance our understanding of structure-adjustment reduction measures' role and highlight their potential advantages and limitations.

Unlocking the Potential of Glutinol: Structural Diversification and Antifungal Activity against Phytopathogenic Fusarium Strains.

Unlike most common pentacyclic plant triterpenes, glutinol has a methyl group at position C-9 and a Δ5 double bond. At the same time, it lacks a methyl at C-10. These features significantly modify its chemical behavior compared to other triterpenes, particularly under oxidative conditions. Although the isolation of glutinol from various plant species has been documented, its chemistry remains largely unexplored. In this study, glutinol was isolated from the bark of Balfourodendron riedelianum as a starting material for top-down strategies of structural diversification, which included ring fusion, oxidation, aromatization, and ring cleavage reactions. Glutinol, together with a library of 22 derivatives, was evaluated for antifungal activity against three phytopathogenic Fusarium strains, F. solani, F. graminearum, and F. tucumaniae. Some of the derivatives displayed antifungal activity; in particular, compound 12, featuring a triazine ring, displayed the best fungicidal properties against F. solani and F. graminearum, while the ring B cleavage product 23 showed the best activity against F. tucumaniae. This study highlights the potential of glutinol as a scaffold for structural diversification, and these results may contribute to the design of novel fungicidal agents against phytopathogenic strains.