Gap Model Research Articles

A new approach to derive productivity of tropical forests using radar remote sensing measurements.

Deriving gross & net primary productivity (GPP & NPP) and carbon turnover time of forests from remote sensing remains challenging. This study presents a novel approach to estimate forest productivity by combining radar remote sensing measurements, machine learning and an individual-based forest model. In this study, we analyse the role of different spatial resolutions on predictions in the context of the Radar BIOMASS mission (by ESA). In our analysis, we use the forest gap model FORMIND in combination with a boosted regression tree (BRT) to explore how spatial biomass distributions can be used to predict GPP, NPP and carbon turnover time (τ) at different resolutions. We simulate different spatial biomass resolutions (4 ha, 1 ha and 0.04 ha) in combination with different vertical resolutions (20, 10 and 2 m). Additionally, we analysed the robustness of this approach and applied it to disturbed and mature forests. Disturbed forests have a strong influence on the predictions which leads to high correlations (R2 > 0.8) at the spatial scale of 4 ha and 1 ha. Increased vertical resolution leads generally to better predictions for productivity (GPP & NPP). Increasing spatial resolution leads to better predictions for mature forests and lower correlations for disturbed forests. Our results emphasize the value of the forthcoming BIOMASS satellite mission and highlight the potential of deriving estimates for forest productivity from information on forest structure. If applied to more and larger areas, the approach might ultimately contribute to a better understanding of forest ecosystems.

Functional outcomes of nerve allografts augmented with mesenchymal stem cells and surgical angiogenesis in a rat sciatic nerve defect model

Motor function recovery following acellular nerve allograft (ANA) repair remains inferior to autologous nerve reconstruction. We investigated the functional recovery of ANAs after combined mesenchymal stem cell (MSC) delivery and surgical angiogenesis in a rat sciatic nerve defect model. In 100 Lewis rats, unilateral sciatic nerve defects were reconstructed with (I) autografts, (II) ANAs, (III) ANAs wrapped with a superficial inferior epigastric artery fascial (SIEF) flap, combined with either (IV) undifferentiated MSCs or (V) Schwann cell-like differentiated MSCs. The tibialis anterior muscle area was evaluated during the survival period using ultrasonography. Functional recovery, histomorphometry, and immunofluorescence were assessed at 12 and 16 weeks. At 12 weeks, the addition of surgical angiogenesis and MSCs improved ankle contractures. The SIEF flap also significantly improved compound muscle action potential (CMAP) outcomes compared with ANAs. Autografts outperformed all groups in muscle force and weight. At 16 weeks, ankle contractures of ANAs remained inferior to autografts and SIEF, whereas the CMAP amplitude was comparable between groups. The muscle force of autografts remained superior to all other groups, and the muscle weight of ANAs remained inferior to autografts. No differences were found in histomorphometry outcomes between SIEF groups and ANAs. Vascularity, determined by CD34 staining, was significantly higher in SIEF groups compared with ANAs. The combination of surgical angiogenesis and MSCs did not result in a synergistic improvement in functional outcomes. In a short nerve gap model, the adipofascial flap may provide sufficient MSCs to ANAs without additional ex vivo MSC seeding.

Prediction of band gap and optimum electrical parameters of a thin homojunction perovskite solar cell based on FA1−xCsxSnyPb1−yI3 through a combination of SCAPS-1D and machine learning based modelling

This paper presents a machine learning (ML) model developed to predict the band gap and optimum electrical parameters of a thin homojunction perovskite solar cell (PSC) based on FA1−xCsxSnyPb1−yI3. For different cesium (x) and tin (y) compositions, band gaps are tabulated, and electrical parameters such as open circuit voltage, short circuit current, and power conversion efficiency are generated in standard test condition (STC) using the SCAPS-1D platform. The data obtained are used to build two sub-models wherein first Model 1 uses the composition to predict the band gap and second Model 2 uses the predicted band gap to predict the electrical parameters using a polynomial regression algorithm. The sub-models are then connected in series. Train and test scores, correlation (r), and root mean square error (RMSE) are calculated to investigate the accuracy of the models while the cross-validation score checks the stability and the overfitting of the models. The final, best performance model’s metrics–R2, r, and RMSE, are 0.99, 0.99, and 0.09 respectively for Model 1 and 0.97, 0.99, and 0.28 for Model 2. These are achieved for a fourth order polynomial. In addition, we realize that the homojunction PSC based on FACsSnPbI3 offers a high efficiency of 17.17% for a band gap of around 1.44 eV. We also reveal that the presence of tin induces lattice contraction, affects the stability, and changes the configuration of the crystal structure from cubic to octahedral tilting when tin composition increases.

Appraising The Relationship Between Foreign Aid On Economic Growth In Nigeria

This paper examines the impact of foreign aid on economic growth and poverty reduction in Nigeria, using the Autoregressive Distributed Lag (ARDL) technique for regression analysis. The study employs time series data from 1986 to 2020 to analyze the long-run and short-run relationship between foreign aid, economic growth in Nigeria. The study adopted the combined theories of economic growth of the Harrod-Domar Model, the Two-Gap Model and the Three- Gap Model in theoretical outlook. The data set is used to test the long-term relationship as well as the short-term relationship. The results show that foreign aid has a positive and significant impact on economic growth and poverty reduction in Nigeria in both the long-run and short run. The study concludes that foreign aid can be an effective tool for promoting economic growth and poverty reduction in Nigeria. The study recommended that in targeting aid towards infrastructure development, foreign aid can be used to fund infrastructure projects like building and upgrading roads, ports, and power plants to create jobs and increase economic activity. It also recommended investing in education and healthcare, foreign aid can be used to support education and healthcare initiatives, to improve the overall health and well-being of the population and increase productivity.

Ex vivo biomechanical evaluation of 2.4 mm LCP plate rod constructs versus 2.7 mm LCP applied to the feline tibia.

To compare the stiffness and strength of three plate and rod fixation constructs applied to a feline tibial gap model. Ex vivo study. Thirty-three unpaired tibiae obtained from skeletally mature cats. The tibiae were randomly divided into three groups. The following implants were then applied to the feline tibiae prior to the creation of a 10 mm diaphyseal gap. Group 1: 2.4 mm locking compression plate (LCP) and 1.0 mm intramedullary pin (IMP). Group 2: 2.4 mm LCP and 1.6 mm IMP. Group 3: 2.7 mm LCP. Subsequently, each specimen was tested for torsion, axial compression, and axial load until construct failure. Student's t-tests were used to compare the torsional and axial stiffness, yield load, and maximum axial force. Group 2 had higher axial stiffness than group 3 (p = .013). Group 1 showed a lower maximum axial force and yield point than groups 2 and 3 (p < .01; p < .05, respectively). There were no among-group differences in torsional stiffness. Constructs with a 2.4 mm LCP and 1.6 mm IMP provided the strongest and most rigid constructs in a feline tibia gap model. A plate-rod construct combining a 2.4 mm LCP and a 1.6 mm IMP is appropriate for achieving high implant stiffness and resisting maximum axial force in treatment of tibial fractures in cats.

Adapting the Digital Servuction Model to Central Banks: Case Study: European Central Bank

Central bank communication has changed over the years, following the trend of digitalization. It has been used as a tool for the implementation of monetary policies since the 1990s, when central banks started publishing their inflation reports, outlooks, and meeting minutes on the road towards greater transparency, and to help meet their price stability mandate. This mandate cannot be achieved through traditional financial instruments alone, so digital communication and marketing has become an economic policy tool. The effectiveness of the European Central Bank’s online communication tools will be tested via a GAP model, by applying an adapted version of the servuction scale to the Bank and disseminating it to 500 citizens, with the purpose of measuring citizen satisfaction with its website and communications. The servuction model focuses on high quality services that are perceived as such by private sector customers, having a strong marketing component. The originality of the research consists in adapting it to the public sector, more specifically to central banks, and by treating citizens as customers throughout the study. The model was successfully applied to the European Central Bank, demonstrating that citizens’ expectations are highest regarding both the reliability and assurance dimensions, meaning that they want to feel confident in ECB actions, and to the understandability dimension of its online content. The largest gaps between citizens’ expectations and perceptions were identified within the efficiency, understandability, and empathy dimensions. In future, the study can be replicated and adapted to both national central banks and private banks within the European Union, assessing how citizens perceive their websites, communication, and marketing strategies, with the purpose of improving the latter two, and increasing civic engagement. The model can also be adapted to narrower topics relating to sustainable digital development, such as the expectations and perceptions of citizens with regards to central bank digital currencies.

Integral micromorphic model for band gap in 1D continuum

Integral micromorphic model for band gap in 1D continuum

Density functional applications of jellium with a local gap model correlation energy functional.

We develop a realistic density functional approximation for the local gap, which is based on a semilocal indicator that shows good screening properties. The local band model has remarkable density scaling behaviors and works properly for the helium isoelectronic series for the atoms of the Periodic Table, as well as for the non-relativistic noble atom series (up to 2022 e-). Due to these desirable properties, we implement the local gap model in the jellium-with-gap correlation energy, developing the local-density-approximation-with-gap correlation functional (named LDAg) that correctly gives correlation energies of atoms comparable with the LDA ones but shows an improvement for ionization potential of atoms and molecules. Thus, LDAg seems to be an interesting and useful tool in density functional theory.

Acoustic Boundary Conditions for Can-Annular Combustors

This paper derives and validates an analytical model for acoustic boundary conditions on a can-annular gas turbine combustion system composed of discrete cans connected to an open annulus upstream of a turbine. The analytical model takes one empirical parameter: a connection impedance between adjacent cans. This impedance is extracted from time-marching computations of two-can sectors of representative combustors. The computations show that reactance follows the Rayleigh conductivity, while resistance takes a value of order 0.1 as a weak function of geometry. With a calibrated value of acoustic resistance, the analytical model reproduces can-to-can transfer functions predicted by full-annulus computations to within 0.03 magnitude at compact frequencies. Varying the combustor–turbine gap length, both model and computations exhibit a minimum in reflected energy, which drops by 63% compared to the datum gap. A parametric study yields a design guideline for gap length at the minimum reflected energy, allowing the designer to maximise transmission from the combustion system and reduce damping requirements.

Thermodynamic Band Gap Model for Photoinduced Phase Segregation in Mixed-Halide Perovskites

Thermodynamic Band Gap Model for Photoinduced Phase Segregation in Mixed-Halide Perovskites

Prediction model of type and band gap for photocatalytic g-GaN-based van der Waals heterojunction of density functional theory and machine learning techniques

Applying suitable two-dimensional (2D) heterojunctions to photocatalytic water cracking reaction can obtain excellent catalytic performance. However, due to many candidate materials and complex interface effects, finding suitable heterojunctions combinations has become a challenge for the above applications. Based on about 1000 pieces of material data in the computational 2D material database, we adopted a simple energy band shift hypothesis to creatively build a machine learning prediction model of g-GaN based 2D Van der Waals (vdW) heterostructures’ type with good performance, and carried out a first-principle calculation to verify the hypothesis. The results show that the band shift hypothesis is valid for the g-GaN based vdW heterojunctions combination without the participation of elements locatedin thefirsttransitional period and this classification model with the area under curve (AUC) value of 0.93. In addition, we further built a regression prediction model for the band gap value of type Ⅱ g-GaN based vdW heterojunctions in line with the band edge position of photocatalytic water-splitting reaction, with a mean absolute error (MAE) of 0.24 eV. This work establishes a machine learning screening process for g-GaN based vdW heterojunction applied in the field of photocatalysis, which greatly improves the research efficiency.

(Don’t) mind the gap? Information gaps compound curiosity yet also feed frustration at work

Although information gaps frequently occur in the workplace, surprisingly little organizational research considered their psychological consequences for employees. We refine the information gap theory by integrating it with the cognitive-affective processing system (CAPS) framework to argue that work-related information gaps constitute a double-edged sword for work engagement because they elicit both specific curiosity and frustration. We find support for our cognitive-affective process model of information gaps across two experience-sampling studies and an experimental study. In Study 1 (74 employees, 270 days), we validated a work-related information gap scale to empirically disentangle information gaps from specific curiosity. In Study 2 (107 employees, 719 days), information gaps were positively associated with specific curiosity and frustration, which in turn had differential effects on work engagement. In Study 3 (405 employees across two conditions), we provide causal support for our model and rule out alternative cognitive (i.e., boredom) and affective (i.e., thriving) mechanisms.

Modelos de calidad de servicio en el suministro público de agua potable en México

To analyze service quality models in the public drinking water supply in Mexico. The paper conducts a systematic review of various works of erudition on the subject, with the models being identified based on their application. A systematic literature review was conducted using the Preferred Reporting Item for Systematic Reviews (PRISMA) and the 3-stage approach by Arksey and O’Malley. The study design was chosen because it helps in the identification of articles through predefined criteria. Electronic searches were conducted via Web of Science and Scopus, with articles published between 1980 and 2022 being identified. The articles were then screened for relevance, applicability, validity, and reliability. The review identified at least five GAPS under the GAP model, which include knowledge, policy, delivery, communication, and consumer. Subsequently, the SERVQUAL model shows that the public drinking water supply systems fall below the set expectations of reliability, assurance, empathy, tangibles, and responsiveness. Contrarily, the government has set up programs like PROME and the Citizens’ Initiatives for General Water Law aimed at improving citizen participation and comprehension of key GAPS in the water supply system. The research is novel as it prods the subject of service quality models in Mexico. This topic is an unexplored area, especially with regard to the GAP and SERVQUAL models. The insight derived from this paper will bridge the existent dearth of knowledge while improving policy formulation and implementation.

Performance of GAP and ILD-GAP models in predicting lung transplant or death in interstitial pneumonia with autoimmune features.

To assess the ability of two risk prediction models in interstitial lung disease (ILD) to predict death or lung transplantation in a cohort of patients with interstitial pneumonia with autoimmune features (IPAF). We performed a retrospective cohort study of adults with IPAF at an academic medical centre. The primary outcome was a composite of lung transplantation or death. We applied the patient data to the previously described Gender-Age-Physiology (GAP) and ILD-GAP models to determine the ability of these models to predict the composite outcome. Model discrimination was assessed using the c-index, and model calibration was determined by comparing the incidence ratios of observed vs expected deaths. Ninety-four patients with IPAF were included. Mean (s.d.) age was 58 (13.5) years and the majority were female (62%). The majority met serologic and morphologic criteria for IPAF (94% and 91%, respectively). The GAP model had a c-index of 0.664 (95% CI 0.547-0.781), while the ILD-GAP model had a c-index of 0.569 (95% CI 0.440-0.697). In those with GAP stage 1 or GAP stage 2 disease, calibration of the GAP model was satisfactory at 2 and 3 years for the cumulative end point of lung transplantation or death. In patients with IPAF, the GAP model performed well as a predictor of lung transplantation or death at 2 years and 3 years from ILD diagnosis in patients with GAP stage 1 and GAP stage 2 disease.

Towards a better understanding of sustainability gaps in retail organizations

ABSTRACT Retailers have been identified as important actors in driving sustainable change, due to their vital role in connecting production and consumption. In this paper, we explore what retailers do to enable consumers to act more sustainable. Whereas there is ample research focusing either on sustainability on the production and sourcing side or on sustainable consumer behaviors, we bridge the two by focusing specifically on consumer-facing sustainability work in grocery retail organizations. Through workshops, interviews, and secondary data, we find a clear ambition among retailers to help consumers behave sustainably. However, our findings also point to several barriers to sustainability work within the organization. The paper concludes by outlining a model of different sustainability ambition-action gaps within retail organizations and possible solutions for closing them.

Static breakdown threshold modeling of quasi-uniform gas gaps with a focus on the PDIV of contacting enameled wire pairs

This paper provides a theoretical and conceptual framework for the determination of static breakdown inception thresholds in quasi-uniform gas gaps bounded by dielectric layers of thickness s and relative permittivity . The special case of uncoated metallic electrodes is included in the limit . Moreover, a review of breakdown mechanisms and the underlying physical processes in quasi-uniform gas gaps is provided, and the applicability of the associated breakdown criteria is discussed. The results include a parametrization of the partial discharge inception voltage of wedge-shaped air gaps at atmospheric pressure as a function of the reduced coating thickness . The predicted results for this prototypical insulation geometry agree well with a broad array of literature data and own measurements. Finally, a physically motivated parametrization of the ionization threshold K(d) is suggested for atmospheric pressure air in terms of secondary electron feedback by energetic photons and ion-enhanced field emission. This contrasts with the ad hoc introduction of modified ‘streamer constants’ often found in literature to explain breakdown voltages that deviate from the predictions of the classical Raether–Meek–Loeb criterion.

Comprehensive analysis of band gap of phononic crystal structure and objective optimization based on genetic algorithm

In this paper, a type of acoustic metamaterial structure is proposed, which provides a new idea for the structural design of metamaterials with specific wave propagation direction. The structure is named snowflake-like square phonon crystal structure (SLS). Firstly, based on Bloch theorem and finite element method, the energy band curve of the structure is obtained, and the low frequency band gap in the range of 300–600Hz is obtained, and the band gap is analyzed comprehensively with the main band gap. It includes the vibration modal analysis at the corresponding point of the boundary of Brillouin zone and the establishment of a corresponding simplified model to explain the mechanism of band gap opening and closing more deeply. At the same time, the band gap characteristic of SLS structure is verified by the transmission curve, and the difference of elastic wave transmission results between inside and outside the band gap is given. Not only that, the real propagation direction of the band gap is described by group velocity and equal frequency diagram. The results show that in the range of relatively low frequency elastic waves, the propagation of elastic waves in the structure has a certain direction and region, that is, the structure can play a good effect of vibration and noise reduction. In addition, after the comprehensive analysis, this paper analyzes the influence trend of various factors on the band gap of the structure, and establishes the optimization model of the target band gap based on genetic algorithm, and finally obtains the optimized SLS structure. The results show that the band gap width is more than 2.5 times larger than the initial band gap width. It shows that even under the specific structure, the optimization space of the band gap still has a high lifting upper limit.

Service Quality and Students' Satisfaction of Management Campuses of Kathmandu Valley

Service quality is a campus strategic tool for increasing student satisfaction. This study was conducted to examine the service quality of management campus from student's perspectives and to assess the relationship and impact of reliability, responsiveness, assurance, empathy and tangible dimensions on satisfaction. A total of 314 management students from bachelor (BBS) and master level (MBS) of management program of five constituent campuses of Tribhuvan University inside Kathmandu Valley were taken through using simple random sampling method. Based on SERVEQUAL gap model developed by the Parasuraman et al. (1985, 1988a), a set of 5-point Likert scale questionnaire was administered to collect data. Result of the result found a poor service quality or negative mean gap in reliability, responsiveness, assurance and tangible dimensions. A strong significant negative impact of mean expectation of responsive dimension was found on service quality gap. On the other hand, mean perception of tangible dimension had strong positive impact on service quality gap. Result of the study emphasizes on the improvement of quality dimensions of management campuses so as to satisfy students and get strategic advantage in this competitive marketplace.

Exploring the configuration space of elemental carbon with empirical and machine learned interatomic potentials

We demonstrate how the many-body potential energy landscape of carbon can be explored with the nested sampling algorithm, allowing for the calculation of its pressure-temperature phase diagram. We compare four interatomic potential models: Tersoff, EDIP, GAP-20 and its recently updated version, GAP-20U. Our evaluation is focused on their macroscopic properties, melting transitions, and identifying thermodynamically stable solid structures up to at least 100 GPa. The phase diagrams of the GAP models show good agreement with experimental results. However, we find that the models’ description of graphite includes thermodynamically stable phases with incorrect layer spacing. By adding a suitable selection of structures to the database and re-training the potential, we have derived an improved model — GAP-20U+gr — that suppresses erroneous local minima in the graphitic energy landscape. At extreme high pressure nested sampling identifies two novel stable structures in the GAP-20 model, however, the stability of these is not confirmed by electronic structure calculations, highlighting routes to further extend the applicability of the GAP models.

Meterwavelength Single Pulse Polarimetric Emission Survey. VI. Toward Understanding the Phenomenon of Pulsar Polarization in Partially Screened Vacuum Gap Model

We have observed 123 pulsars with periods longer than 0.1 s in the Meterwavelength Single Pulse Polarimetric Emission Survey. In this work, a detailed study of the polarization behavior of these pulsars has been carried out. We were able to fit the rotating vector model to the polarization position angle sweeps in 68 pulsars, and in 34 pulsars the emission heights could be measured. In all cases the radio emission was constrained to arise below 10% of the light cylinder radius. In pulsars with low spin-down energy loss, erg s−1, we found the mean fractional linear polarization of the individual time samples in single pulses to be around 0.57 (57%), which is significantly larger than the fractional linear polarization of 0.29 (29%) obtained from the average profiles. On the other hand, the mean fractional circular polarization of the individual time samples in single pulses is around 0.08 (8%), similar to the measurements from the average profiles. To explain the observed polarization features, we invoke the partially screened vacuum gap model of pulsars, where dense spark-associated plasma clouds exist with high pair plasma multiplicity, with significant decrease of density in the regions between the clouds that are dominated by iron ions. The coherent radio emission is excited by curvature radiation from charge bunches in these dense plasma clouds and escape as linearly polarized waves near cloud boundaries. We suggest that the circular polarization arises due to propagation of waves in the low-pair-multiplicity, ion-dominated inter-cloud regions.