Active Space Research Articles

The Localized Active Space Method with Unitary Selective Coupled Cluster.

We introduce a hybrid quantum-classical algorithm, the localized active space unitary selective coupled cluster singles and doubles (LAS-USCCSD) method. Derived from the localized active space unitary coupled cluster (LAS-UCCSD) method, LAS-USCCSD first performs a classical LASSCF calculation, then selectively identifies the most important parameters (cluster amplitudes used to build the multireference UCC ansatz) for restoring interfragment interaction energy using this reduced set of parameters with the variational quantum eigensolver method. We benchmark LAS-USCCSD against LAS-UCCSD by calculating the total energies of (H2)2, (H2)4, and trans-butadiene, and the magnetic coupling constant for a bimetallic compound [Cr2(OH)3(NH3)6]3+. For these systems, we find that LAS-USCCSD reduces the number of required parameters and thus the circuit depth by at least 1 order of magnitude, an aspect which is important for the practical implementation of multireference hybrid quantum-classical algorithms like LAS-UCCSD on near-term quantum computers.

Impacts of Dacwah Activities of Selected Muslim Scholars on Social Media Platforms on Yoruba Muslims

Social media has become an integral part of Muslims' personal and public lives. Through the advancement of the Internet, Social media networks such as Facebook, Twitter, Instagram, YouTube, WhatsApp, Telegram, Tik-Tok and personal blogs have gloriously allocated space for Dacwah activities. Thus, this study aims to assess the utilization of Social media platforms by selected Yoruba Muslim scholars for Dacwah activities and the impacts they have on Yoruba Muslims. Descriptive and analytical methods of research have been employed in carrying out this research. The descriptive method assists in describing how social media platforms are utilized by selected Yoruba Muslim scholars. The analytical method helps in analyzing the content of social media post by Yoruba Muslim scholars. Participatory observation, as a research tool, is used to follow some Ducāt in order to have access to their discussions and posts as well as get information on their impacts. The paper reveals that, as a result of advance in modern information dissemination, social media has provided innovative platforms for religious leaders to spread their messages and engage with various Muslims conveniently. The paper also reveals the effectiveness of religious scholars’ message in influencing attitudes, behaviors and perceptions among their followers. The paper concludes that the role of Social media in fostering unity, promoting values, and countering misconceptions about Islam cannot be underestimated. Therefore, it is recommended that the Yoruba Muslim scholars should make strategic use of Social media positively to impacts the Nigerian Muslims by disseminating knowledge fostering unity and countering misinformation.

Computational Modeling of the Conformation-Dependent Atmospheric Reactivity of Criegee Intermediates.

The impacts of Criegee intermediates (CIs) on atmospheric chemistry depend significantly on the CI conformation. In this Perspective, I highlight examples of how electronic structure and statistical rate theory calculations, in conjunction with experiment, have revealed conformation-dependent details of both CI ground-state reactivity and electronic excitation. Calculations using single-reference electronic structure methods and conventional transition state theory have predicted that CIs with syn-alkyl or syn-vinyl substituents isomerize rapidly to vinyl hydroperoxides (VHPs) or dioxoles, both of which can decompose rapidly under atmospheric conditions. Ongoing computational research on hydroxyl radical (OH) roaming initiated by VHP dissociation requires the application of multireference electronic structure methods and variational transition state theory. CIs that lack both syn-alkyl and syn-vinyl substituents undergo either bimolecular reaction or π* ← π electronic excitation in the atmosphere. Accurate predictions of CI ultraviolet-visible spectra require multireference calculations with large active spaces and at least a second-order perturbative treatment of dynamic electron correlation. The extent to which electronic spectra can be diagnostic of the presence of specific CI conformers varies significantly with CI chemical identity.

The economic displacement of thousands of fishers in the Pantanal, Brazil: A telling story of small‐scale fisheries marginalization worldwide.

AbstractA new policy in the Pantanal wetland, Brazil, aims to economically displace thousands of artisanal fishers from one‐third of the region. The legislation disregards several FAO Voluntary Guidelines for Securing Sustainability in Small‐Scale Fisheries' guiding principles (SSF guidelines). Considering that 2024 marks the 10th anniversary of these guidelines, this policy represents a significant setback for fish and fisheries worldwide. In this paper, we show that the legislation is part of long‐term agenda against small‐scale fishers in the Pantanal, aiming to use narratives around overfishing to justify physical and economic displacements—albeit no empirical evidence showing impact on fish stocks. We also show that, as in many other small‐scale fisheries worldwide, overfishing narratives are, in fact, used to open space for industrial activities and large infrastructure projects. The Pantanal is a telling story of that, since the new legislation will likely open space for the construction of over 50 small hydroelectric dams in the Pantanal and surrounding area. We argue that, first, it is urgent to abolish the new legislation and promote a pro‐fishers agenda in the Pantanal to protect the region. However, since this is not unique for the region, it is critical to implement international programmes that celebrate and support local fisheries worlwide and avoid physical and economic displacements. Stands out turning SSF guidelines into international agreements, implementing citizens science programmes and expanding the fisher's tenure rights through innovative mechanizes of ownership. By better protecting local small‐scale fishers in the Pantanal and worldwide we are more likely to guarantee a sustainable future for ecosystems and its peoples.

Employing Metadynamics to Predict the Membrane Partitioning of Carboxy-2H-Azirine Natural Products.

Natural products containing the carboxy-2H-azirine moiety are an exciting target for investigation due to their broad-spectrum antimicrobial activity and new chemical space they afford for novel therapeutic development. The carboxy-2H-azirine moiety, including those appended to well-characterized chemical scaffolds, is understudied, which creates a challenge for understanding potential modes of inhibition. In particular, some known natural product carboxy-2H-azirines have long hydrophobic tails, which could implicate them in membrane-associated processes. In this study, we examined a small set of carboxy-2H-azirine natural products with varied structural features that could alter membrane partitioning. We compared the predicted membrane partitioning and alignment of these compounds to those of established membrane embedders with similar chemical scaffolds. To accomplish this, we developed parameters within the framework of the CHARMM36 force field for the 2H-azirine functional group and performed metadynamics simulations of the partitioning into a model bacterial membrane from aqueous solution. We determined that the carboxy-2H-azirine functional group is strongly hydrophilic, imbuing the long-chain natural products with amphipathicity similar to the known membrane-embedding molecules to which they were compared. For the long-chain analogs, the carboxy-2H-azirine head group stays within 1 nm of the phosphate layer, while the hydrophobic tail sits within the membrane. The carboxy-2H-azirine lacking the long alkyl chain instead partitions completely into aqueous solution.

Numerical analysis of the complete active-space extended Koopmans's theorem.

We investigate the numerical accuracy of the extended Koopmans's theorem (EKT) in reproducing the full configuration interaction (FCI) and complete active-space configuration interaction (CAS-CI) ionization energies (IEs) of atomic and molecular systems calculated as the difference between the energies of N and (N - 1) electron states. In particular, we study the convergence of the EKT IEs to their exact values as the basis set and the active space sizes vary. We find that the first FCI EKT IEs approach their exact counterparts as the basis set size increases. However, increasing the basis set or the active space sizes does not always lead to more accurate CAS-CI EKT IEs. Our investigation supports the observation of Davidson et al. [J. Chem. Phys. 155, 051102 (2021)] that the FCI EKT IEs can be systematically improved with arbitrary numerical accuracy by supplementing the basis set with diffuse functions of appropriate symmetry, which allow the detached electron to travel far away from the reference system. By changing the exponent and the center of the diffuse functions, our results delineate a complex pattern for the CAS-CI EKT IE of LiH, which can be important for the spectroscopic studies of small molecules.

Small-Scale Pig Farming as a Tool for Unemployment Alleviation in Buffalo City, Eastern Cape of South Africa

The study examines the effect of small-scale pig farming on unemployment alleviation in Buffalo City, Eastern Cape of South Africa. This is against the backdrop of the extreme youth unemployment and increasing poverty rate being witnessed in South Africa (SA) due to the unstable global economic environment that has impacted most economies of the world. On its part, the government made an appreciable number of investments, especially in the agricultural sector, to address the unemployment challenges, which has yielded varied levels of success. The unemployment situation in SA was compounded by the COVID-19 pandemic, which resulted in approximately 33% of the labour resources that were productive before the pandemic to idle. This necessitated a government injection of R100 billion as a stimulus package into the economy to support small businesses and the agricultural sector, especially small-scale farmers. Mixed methods were adopted to gather primary data from 164 pig farmers, which were randomly selected. XLSTAT and SPSS 28 were used to analyse the quantitative data, and NVivo was used for the qualitative data. The results revealed that farming activities provided a source of income for most pig farmers, with several households depending on it for their livelihood. The collective advantage among pig farmers was the availability of space for farming activities, and most of them engaged in pig farming as a necessity. The government plays a crucial role in the sustainability of pig farming activities in the area through the various interventions that create the needed enabling environment for the farmers to thrive.

Comparative analyses of publicness in urban squares within a diversifying metropolis

AbstractEnsuring publicness and accommodating more diverse human activity in urban public spaces is necessary. This research analyses the relationship between human activities, ownership, and physical features encouraging or discouraging use within the city centre of Dublin (Ireland), a diversifying metropolis experiencing dereliction. Four urban squares were assessed through fieldwork, including direct observation and behavioural mapping. Results indicate that publicness and features encouraging or discouraging use are not directly associated with site ownership. Nor was the presence of nature and landscaping determined by ownership, though it generated microclimates that promoted a higher mix of activities. Implications of going beyond formal definitions of ownership for publicness placed under broader sustainability agendas and recommendations for urban design practice are derived.

Evaluation of pulpal blood flow during orthodontic space closure: Prospective clinical trial

Orthodontic tooth movement (OTM) is a biological process that can affect the vascularization of the dental pulp. The forces exerted on the teeth may increase periapical pressure that could compress the arterioles, which in turn affects pulpal blood flow (PBF). The study aimed to investigate how OTM affects PBF during orthodontic space closure. A total of 22 adolescent participants who required orthodontic space closure in mandibular posterior sectors were enrolled in a prospective clinical study. The same sliding mechanics, wires, and active elements were used. Patients were observed before OTM, after leveling before space closure, and at the 4th, 7th, 21st, and 28th during active space closure. PBF was measured with laser Doppler (LD) flowmetry. Dental models were obtained with an intraoral scanner. The LD flow values decreased significantly during the observation period (2-way repeated measures analysis of variance, P<0.001). There was a significant difference in LD flow between tooth categories (2-way repeated measures analysis of variance, P<0.001). During space closure, the most pronounced LD flow reduction was observed in single-rooted teeth closest to the residual space. A higher speed of OTM was associated with a greater decrease in LD flow on day 4 of OTM (Pearson correlation, P= 0.0299). Orthodontic space closure reduced PBF; it was lowest in the early stages of space closure and showed a tendency to increase during the first month. Anterior teeth closer to the interdental space that experiences more OTM and teeth that move faster during initial OTM had a higher risk of reduced blood flow.

Advancing Our Understanding of the Excited States of the Tantalum Anion.

Our study provides a comprehensive theoretical examination of the energy levels associated with the neutral tantalum atom and its ions in various charge states (Ta, Ta+, and Ta-), employing the multiconfiguration Dirac-Hartree-Fock (MCDHF) method, and relativistic infinite order two-component (IOTC) method with multiconfiguration complete active space self-consistent field (CASSCF) followed by the second-order single-state multireference perturbation (CASPT2) methods. The effect of spin-orbit (SO) coupling is introduced via the restricted active space state interaction (RASSI) method, utilizing atomic mean field SO integrals (AMFI). Through IOTC CASSCF/CASPT2 RASSI calculations, we determined the electron affinity (EA) of the tantalum atom to be 0.321 eV, which stands among the most accurate theoretical values achieved to date. This result closely aligns with the experimental measurement of 0.329 eV. Our investigation highlights potential discrepancies between the predicted symmetry of the excited states of the tantalum anion and experimental observations. Additionally, we calculated the bonding energies for transitions from Ta- to Ta and identified four potential bound or quasi-bound states in the tantalum anion.

Digitalization and Cyber Security Policies in Uzbekıstan's Institutions and Sectors in One Belt One Road Project

The diffusion of information and communication technologies (ICT) into a rapidly growing area of global trade has contributed significantly to the gains made by companies and governments. Increasing consumption at the international level and the desire for faster and more reliable delivery of goods have led to the emergence of new sectors. In this context, states, other government agencies, and the private sector have sought to enhance their bilateral relations and investments and establish strategic partnerships to develop new fast, and reliable trade networks. While actions and activities in cyberspace and digital spaces have provided significant convenience and opportunities, they have also led to significant security concerns. The purpose of this study is to examine and evaluate the contribution of the One Belt, One Road (OBOR) initiative to the digitalization of Uzbekistan and the policies pursued by Uzbekistan in this regard, and to investigate the effects of public and private sector institutional cooperation in the One Belt, One Road project. The content analysis method was applied, one of the qualitative research methods. The study was also strengthened with the SWOT analysis method. By comparing relevant documents and sources on the subject, the aim of the study was concluded. The studies carried out to increase Uzbekistan's cyber capacity, the importance of maintaining strong cyber security policies through technology transfer, the challenges and legal regulations, institutional and sectoral cooperation, and their effects are the problem statements within the outline of the purpose of the study.

‘I’ve just heard that there are people who feel like they need to exercise’: a photo-elicitation study of values and priorities influencing physical activity in a socioeconomically disadvantaged neighbourhood in Uppsala, Sweden

ObjectivePeople living in socioeconomically disadvantaged neighbourhoods in Sweden engage less in physical activity compared with the general population, contributing to an elevated risk of cardiometabolic diseases. To inform targeted and...

Tourism in rural areas as a broader concept: Some insights from the Portuguese reality

Abstract For sustainable rural development, the complementarity between the socioeconomic activities developed in rural areas is fundamental to create synergies and economic dynamics with positive externalities for the populations in less favoured spaces. The great challenge for the rural regions is the creation of attractive employment to avoid the desertification of these areas and the respective consequences. Some of the impacts of the rural exodus are related to the agroforestry activities abandonment and the increase of biomass in the respective land which, in certain circumstances, is fuel for forest fires. Tourism in rural areas/space (TRA/S) may contribute significantly to improving the complementarity among activities in less favoured spaces and promoting sustainability in mentioned areas. From this perspective, this research aims to explore dimensions associated with TRA/S, highlighting the main contributions from the scientific literature and showing that it can be considered, in some contexts, a broader concept than the concept of rural tourism. To achieve these objectives, first a systematic review based on metrics from the bibliometric analysis was carried out, considering 165 documents found in the Scopus database in a search performed on 19 March 2024 for the following topics and conditions: “tourism in rural areas” or “tourism in rural space.” Then, statistics on the Portuguese reality are presented and analysed, highlighting evidence of the context in Portugal. The findings obtained from the systematic review and bibliometric analysis show the importance of this economic activity for the rural regions and reveal some gaps in the literature that may be considered in future studies, namely the following: the links between tourism in rural areas and economic dynamics should be further developed, further address the interconnection between TRA/S dynamics and the Sustainable Development Goals, and more knowledge about the particularities of each Portuguese context. The statistical analysis of the Portuguese context shows that tourism in rural areas has benefited from the pandemic; it seems that tourists have discovered this form of tourism.

Modeling Photodissociation: Quantum Dynamics Simulations of Methanol.

A comprehensive computational study of the gas-phase photodissociation dynamics of methanol is presented. Using a multiconfigurational active space based method (RASSCF) to obtain multidimensional potential energy surfaces (PESs) on-the-fly, direct quantum dynamics simulations were run using the variational multi-configurational Gaussian method (DD-vMCG). Different initial excitation energies were simulated to investigate the dependence of the branching ratios on the electronic state being populated. A detailed mechanistic explanation is provided for the observed differences with respect to the excitation energy. Population of the lowest lying excited state of methanol leads to rapid hydroxyl hydrogen loss as the main dissociation channel. This is rationalized by the strongly dissociative nature of the PES cut along the O-H stretching coordinate, confirmed by the broad feature in the absorption spectrum. In contrast, more energetic excitations lead mainly to C-O bond breaking. Again, analysis of the diabatic surfaces offers a clear explanation in terms of the nature of the electronic states involved and the coupling between them. The type of calculations presented, as well as the subsequent analysis of the results, should be seen as a general workflow for the modeling of photochemical reactions.

Socio-spatial segregation in residents’ daily life: A longitudinal study in Beijing

Segregation studies based on human activity spaces have attracted increasing interest in urban geography and planning. Previously, most research employed variations in the geographical features of individuals' physical activity areas to ascertain social group segregation. A few studies have examined segregation based on one's activity space, comparing this over several years. This research conducts an empirical analysis based on people's activity space in Beijing to detect changes in segregation over time. We investigate activity space-based segregation among Beijing residents, separated into four housing categories for inner-city and suburban areas. The primary outcomes show residents living in different types of housing experience varying degrees of segregation when considering their activity spaces, which has progressed over the years. Furthermore, the findings show that the impact of changes in the built environment on the socio-spatial segregation of residents is gradually deepening, while the impact of institutional contexts such as danwei is gradually decreasing. In summary, this paper provides Beijing-based empirical evidence for this housing type differentiation and increasing segregation, which helps to enrich the understanding of activity space-based socio-spatial segregation of urban residents in China.

Rural activity spaces integration with creative market models

AbstractAs urbanization advances and societal shifts unfold, the integration of rural development and activity spaces has become a focal point in academic discourse. This study aims to explore the synergistic effects of the creative market model on rural activity spaces, dissecting its role in shaping these spaces, enhancing community engagement, and generating socio-economic benefits. Empirical findings highlight the affirmative role of the creative market model in this fusion. The research on community participation and spatial design reveals how creative markets enhance residents' sense of involvement and explores the influence of activity space design on community interaction. This study, by thoroughly examining the integration of the creative market model and rural activity spaces, offers theoretical and empirical support for advancing rural development.

University Population and Wildfire Risk: An Analysis of Perception-Based Variables and Geospatial Differences

This research presents a novel perspective on university students, staff, and faculty and their perception of risk concerning wildfires in the fire-prone US State of Idaho. Past studies have conducted resident surveys in high-risk communities to investigate what factors make homeowners more likely to engage in mitigation activities, increasing communities’ resiliency. Research on a population without property ownership and using the wildland-urban interface (WUI) as activity and recreation spaces is limited. The main hypothesis is that a university population will have different perception and awareness levels in perception-based variables when comparing students to staff/faculty in a traditional survey and geospatial analysis. This study investigates Boise State University’s population’s risk perception using an online survey and interactive spatial assessment to examine differences between associated and geographically allocated risk spaces. Findings from perception mapping, binomial regression, and geostatistical analysis contrast current literature with traditional residents’ surveys. The explorative geostatistical analysis reveals distinct allocation patterns of perceived risk not captured in survey questions. Overall, findings promote a better understanding of where risk and awareness are apparent and suggest that wildfire communication efforts should reach out to all users of the WUI.

Optimization Study of Outdoor Activity Space Wind Environment in Residential Areas Based on Spatial Syntax and Computational Fluid Dynamics Simulation

In the context of increasing global energy shortages and climate change, the human living environment, as a crucial component of residents’ daily lives, has garnered growing attention from the academic community. Research on residential environments is vital for promoting the sustainable development of urban construction and constitutes an important aspect of sustainable development studies. This study focuses on the optimization strategy for the outdoor activity space wind environment in the Xihuayuan residential area in Lanzhou city, utilizing spatial syntax analysis and Computational Fluid Dynamics (CFD) simulation technology. Firstly, the outdoor activity space is analyzed for visibility and spatial accessibility using DepthmapX0.6 software. Then, the outdoor wind environment in the residential area is simulated using PHOENICS 2018 software, and the analysis is conducted on outdoor spaces with a poor wind environment in terms of high accessibility. The results indicate that residents’ outdoor comfort in these spaces is poor, highlighting the urgent need for improvement in the wind environment. This research attempts to optimize the wind environment in high-accessibility spaces within the residential area by improving building layout, orientation, and height. The simulation results after optimization demonstrate an increase in the overall average wind speed to 1.44 m/s, with the proportion of spaces with a good wind environment in high-accessibility areas during summer rising from 33.4% to 59.2%. The optimization strategy effectively improves the wind environment in high-accessibility areas of the residential area.

A joint time and spatial attention-based transformer approach for recognizing the behaviors of wild giant pandas

Wild giant pandas, an endangered species exclusive to China, are a focus of conservation efforts. The behavior of giant pandas reflects their health conditions and activity capabilities, which play an important role in formulating and implementing conservation measures. Researching and developing efficient behavior recognition methods based on deep learning can significantly advance the study of wild giant panda behavior. This study introduces, for the first time, a transformer-based behavior recognition method termed PandaFormer, which employs time-spatial attention to analyze behavioral temporal patterns and estimate activity spaces. The method integrates advanced techniques such as cross-fusion recurrent time encoding and transformer modules, which handle both temporal dynamics and spatial relationships within panda behavior videos. First, we design cross-fusion recurrent time encoding to represent the occurrence time of behaviors effectively. By leveraging the multimodal processing capability of the transformer, we input time and video tokens into the transformer module to explore the relation between behavior and occurrence time. Second, we introduce relative temporal weights between video frames to enable the model to learn sequential relationships. Finally, considering the fixed position of the camera during recording, we propose a spatial attention mechanism based on the estimation of the panda's activity area. To validate the effectiveness of the model, a video dataset of wild giant pandas, encompassing five typical behaviors, was constructed. The proposed method is evaluated on this video-level annotated dataset. It achieves a Top-1 accuracy of 92.25 % and a mean class precision of 91.19 %, surpassing state-of-the-art behavior recognition algorithms by a large margin. Furthermore, the ablation experiments validate the effectiveness of the proposed temporal and spatial attention mechanisms. In conclusion, the proposed method offers an effective way of studying panda behavior and holds potential for application to other wildlife species.

Modeling pedestrians' activity time-use choices in a virtual urban public space: The influences of the environment and affective experience

Understanding pedestrians' time-use choices for multiple activities in urban public spaces is crucial for developing diverse and inclusive public spaces. Few studies have explored how pedestrians' time-use choices are influenced by the physical environment when engaging in various micro-level activities in public spaces, nor have they captured the influence of experience-based factors (e.g., emotion and perceptions) triggered by varying environments, as well as heterogeneity between individuals. This study employs the multiple discrete-continuous extreme value (MDCEV) model to estimate the effects of public space environmental attributes, visit purpose, emotion, and perceptions on individuals' activity time-use choices using data collected in varying virtual hypothetical public spaces. A latent class MDCEV model incorporating personal variables is used to further examine individual heterogeneity. The results indicate that outdoor dining spaces and benches significantly promote outdoor activities. Emotional pleasure and arousal, as well as perceived legibility and liveness, significantly influence various activities in varying ways and to varying degrees. Differences in activity time-use choice patterns between two groups are revealed - one more emotionally driven and the other more cognitively driven. The results complement existing knowledge of pedestrians' activities and inform the planning and design decisions for positive human-environment interactions in urban public spaces.