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10,073
result(s) for
"technology gap analysis"
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Technology Gap Analysis on the BIM-Enabled Design Process of Prefabricated Buildings: An Autoethnographic Study
2024
This research explores the pivotal role of Building Information Modeling (BIM) technology in revolutionizing the design and construction of prefabricated buildings. It highlights the benefits of BIM-enabled design processes, including improved coordination and efficiency, while addressing challenges in integrating BIM with prefabricated elements. The study proposes artificial intelligence (AI) solutions to enhance architectural detailing, optimize workflows, and facilitate human–robot collaboration. Using autoethnographic methods, the research refines BIM-forward design through thematic analysis and technology gap (TG) assessments. It advocates for a comprehensive technology roadmap that emphasizes BIM libraries, external data sources, and the transition to a multi-dimensional BIM environment. This research contributes valuable insights to advance BIM practices in prefabricated building construction and offers a strategic framework to bridge existing TGs, enabling seamless integration of BIM and AI in future practices.
Journal Article
Structure of native lens connexin 46/50 intercellular channels by cryo-EM
2018
Gap junctions establish direct pathways for cell-to-cell communication through the assembly of twelve connexin subunits that form intercellular channels connecting neighbouring cells. Co-assembly of different connexin isoforms produces channels with unique properties and enables communication across cell types. Here we used single-particle cryo-electron microscopy to investigate the structural basis of connexin co-assembly in native lens gap junction channels composed of connexin 46 and connexin 50 (Cx46/50). We provide the first comparative analysis to connexin 26 (Cx26), which—together with computational studies—elucidates key energetic features governing gap junction permselectivity. Cx46/50 adopts an open-state conformation that is distinct from the Cx26 crystal structure, yet it appears to be stabilized by a conserved set of hydrophobic anchoring residues. ‘Hot spots’ of genetic mutations linked to hereditary cataract formation map to the core structural–functional elements identified in Cx46/50, suggesting explanations for many of the disease-causing effects.
Cryo-electron microscopy structures of connexin channels composed of connexin 46 and connexin 50 in an open-state reveal features that govern permselectivity and the location of mutated residues linked to herediatry cataracts.
Journal Article
Active learning narrows achievement gaps for underrepresented students in undergraduate science, technology, engineering, and math
by
Chambwe, Nyasha
,
Keller, Marlowe
,
Sundaravardan, Vasudha
in
Active learning
,
Bayesian analysis
,
Classrooms
2020
We tested the hypothesis that underrepresented students in active-learning classrooms experience narrower achievement gaps than underrepresented students in traditional lecturing classrooms, averaged across all science, technology, engineering, and mathematics (STEM) fields and courses. We conducted a comprehensive search for both published and unpublished studies that compared the performance of underrepresented students to their overrepresented classmates in active-learning and traditional-lecturing treatments. This search resulted in data on student examination scores from 15 studies (9,238 total students) and data on student failure rates from 26 studies (44,606 total students). Bayesian regression analyses showed that on average, active learning reduced achievement gaps in examination scores by 33% and narrowed gaps in passing rates by 45%. The reported proportion of time that students spend on in-class activities was important, as only classes that implemented high-intensity active learning narrowed achievement gaps. Sensitivity analyses showed that the conclusions are robust to sampling bias and other issues. To explain the extensive variation in efficacy observed among studies, we propose the heads-and-hearts hypothesis, which holds that meaningful reductions in achievement gaps only occur when course designs combine deliberate practice with inclusive teaching. Our results support calls to replace traditional lecturing with evidence-based, active-learning course designs across the STEM disciplines and suggest that innovations in instructional strategies can increase equity in higher education.
Journal Article
Transcriptomic and morphophysiological evidence for a specialized human cortical GABAergic cell type
by
Novotny, Mark
,
Faragó, Nóra
,
Oláh, Gáspár
in
Brain research
,
Cholecystokinin
,
Combinatorial analysis
2018
We describe convergent evidence from transcriptomics, morphology, and physiology for a specialized GABAergic neuron subtype in human cortex. Using unbiased single-nucleus RNA sequencing, we identify ten GABAergic interneuron subtypes with combinatorial gene signatures in human cortical layer 1 and characterize a group of human interneurons with anatomical features never described in rodents, having large ‘rosehip’-like axonal boutons and compact arborization. These rosehip cells show an immunohistochemical profile (GAD1+CCK+, CNR1–SST–CALB2–PVALB–) matching a single transcriptomically defined cell type whose specific molecular marker signature is not seen in mouse cortex. Rosehip cells in layer 1 make homotypic gap junctions, predominantly target apical dendritic shafts of layer 3 pyramidal neurons, and inhibit backpropagating pyramidal action potentials in microdomains of the dendritic tuft. These cells are therefore positioned for potent local control of distal dendritic computation in cortical pyramidal neurons.
Journal Article
Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites
by
Pareek, Vivek
,
Doherty, Tiarnan A. S.
,
Tennyson, Elizabeth M.
in
Clusters
,
Correlation analysis
,
Crystal defects
2020
Halide perovskite materials have promising performance characteristics for low-cost optoelectronic applications. Photovoltaic devices fabricated from perovskite absorbers have reached power conversion efficiencies above 25 per cent in single-junction devices and 28 per cent in tandem devices
1
,
2
. This strong performance (albeit below the practical limits of about 30 per cent and 35 per cent, respectively
3
) is surprising in thin films processed from solution at low-temperature, a method that generally produces abundant crystalline defects
4
. Although point defects often induce only shallow electronic states in the perovskite bandgap that do not affect performance
5
, perovskite devices still have many states deep within the bandgap that trap charge carriers and cause them to recombine non-radiatively. These deep trap states thus induce local variations in photoluminescence and limit the device performance
6
. The origin and distribution of these trap states are unknown, but they have been associated with light-induced halide segregation in mixed-halide perovskite compositions
7
and with local strain
8
, both of which make devices less stable
9
. Here we use photoemission electron microscopy to image the trap distribution in state-of-the-art halide perovskite films. Instead of a relatively uniform distribution within regions of poor photoluminescence efficiency, we observe discrete, nanoscale trap clusters. By correlating microscopy measurements with scanning electron analytical techniques, we find that these trap clusters appear at the interfaces between crystallographically and compositionally distinct entities. Finally, by generating time-resolved photoemission sequences of the photo-excited carrier trapping process
10
,
11
, we reveal a hole-trapping character with the kinetics limited by diffusion of holes to the local trap clusters. Our approach shows that managing structure and composition on the nanoscale will be essential for optimal performance of halide perovskite devices.
Photoemission electron microscopy images of trap states in halide peroskites, spatially correlated with their structural and compositional factors, may help in managing power losses in optoelectronic applications.
Journal Article
The confidence gap predicts the gender pay gap among STEM graduates
by
Wang, Shiya
,
Thompson, Marissa E.
,
Sterling, Adina D.
in
Correlation analysis
,
Culture
,
Empirical Research
2020
Women make less than men in some science, technology, engineering, and math (STEM) fields. While explanations for this gender pay gap vary, they have tended to focus on differences that arise for women and men after they have worked for a period of time. In this study we argue that the gender pay gap begins when women and men with earned degrees enter the workforce. Further, we contend the gender pay gap may arise due to cultural beliefs about the appropriateness of women and men for STEM professions that shape individuals’ self-beliefs in the form of self-efficacy. Using a three-wave NSF-funded longitudinal survey of 559 engineering and computer science students that graduated from over two dozen institutions in the United States between 2015 and 2017, we find women earn less than men, net of human capital factors like engineering degree and grade point average, and that the influence of gender on starting salaries is associated with self-efficacy. We find no support for a competing hypothesis that the importance placed on pay explains the pay gap; there is no gender difference in reported importance placed on pay. We also find no support for the idea that women earn less because they place more importance on workplace culture; women do value workplace culture more, but those who hold such values earn more rather than less. Overall, the results suggest that addressing cultural beliefs as manifested in self-beliefs—that is, the confidence gap—commands attention to reduce the gender pay gap.
Journal Article
Bismuthene on a SiC substrate
2017
Quantum spin Hall materials hold the promise of revolutionary devices with dissipationless spin currents but have required cryogenic temperatures owing to small energy gaps. Here we show theoretically that a room-temperature regime with a large energy gap may be achievable within a paradigm that exploits the atomic spin-orbit coupling. The concept is based on a substrate-supported monolayer of a high–atomic number element and is experimentally realized as a bismuth honeycomb lattice on top of the insulating silicon carbide substrate SiC(0001). Using scanning tunneling spectroscopy, we detect a gap of ~0.8 electron volt and conductive edge states consistent with theory. Our combined theoretical and experimental results demonstrate a concept for a quantum spin Hall wide-gap scenario, where the chemical potential resides in the global system gap, ensuring robust edge conductance.
Journal Article
Band gap formation and Anderson localization in disordered photonic materials with structural correlations
by
Engel, Michael
,
Sáenz, Juan José
,
Froufe-Pérez, Luis S.
in
Anderson localization
,
Coding
,
Computer simulation
2017
Disordered dielectric materials with structural correlations show unconventional optical behavior: They can be transparent to long-wavelength radiation, while at the same time have isotropic band gaps in another frequency range. This phenomenon raises fundamental questions concerning photon transport through disordered media. While optical transparency in these materials is robust against recurrent multiple scattering, little is known about other transport regimes like diffusive multiple scattering or Anderson localization. Here, we investigate band gaps, and we report Anderson localization in 2D disordered dielectric structures using numerical simulations of the density of states and optical transport statistics. The disordered structures are designed with different levels of positional correlation encoded by the degree of stealthiness χ. To establish a unified view, we propose a correlation-frequency (χ–ν) transport phase diagram. Our results show that, depending only on χ, a dielectric material can transition from localization behavior to a band gap crossing an intermediate regime dominated by tunneling between weakly coupled states.
Journal Article
Gap-junction-mediated cell-to-cell communication
2013
Cells of multicellular organisms need to communicate with each other and have evolved various mechanisms for this purpose, the most direct and quickest of which is through channels that directly connect the cytoplasms of adjacent cells. Such intercellular channels span the two plasma membranes and the intercellular space and result from the docking of two hemichannels. These channels are densely packed into plasma-membrane spatial microdomains termed “gap junctions” and allow cells to exchange ions and small molecules directly. A hemichannel is a hexameric torus of junctional proteins around an aqueous pore. Vertebrates express two families of gap-junction proteins: the well-characterized connexins and the more recently discovered pannexins, the latter being related to invertebrate innexins (“invertebrate connexins”). Some gap-junctional hemichannels also appear to mediate cell-extracellular communication. Communicating junctions play crucial roles in the maintenance of homeostasis, morphogenesis, cell differentiation and growth control in metazoans. Gap-junctional channels are not passive conduits, as previously long regarded, but use “gating” mechanisms to open and close the central pore in response to biological stimuli (e.g. a change in the transjunctional voltage). Their permeability is finely tuned by complex mechanisms that have just begun to be identified. Given their ubiquity and diversity, gap junctions play crucial roles in a plethora of functions and their dysfunctions are involved in a wide range of diseases. However, the exact mechanisms involved remain poorly understood.
Journal Article
Unconventional chiral charge order in kagome superconductor KV3Sb5
by
Zhang, Qi
,
Wang, Ziqiang
,
Chang, Guoqing
in
639/301/119/2792/4128
,
639/301/119/2794
,
639/766/119/995
2021
Intertwining quantum order and non-trivial topology is at the frontier of condensed matter physics
1
–
4
. A charge-density-wave-like order with orbital currents has been proposed for achieving the quantum anomalous Hall effect
5
,
6
in topological materials and for the hidden phase in cuprate high-temperature superconductors
7
,
8
. However, the experimental realization of such an order is challenging. Here we use high-resolution scanning tunnelling microscopy to discover an unconventional chiral charge order in a kagome material, KV
3
Sb
5
, with both a topological band structure and a superconducting ground state. Through both topography and spectroscopic imaging, we observe a robust 2 × 2 superlattice. Spectroscopically, an energy gap opens at the Fermi level, across which the 2 × 2 charge modulation exhibits an intensity reversal in real space, signalling charge ordering. At the impurity-pinning-free region, the strength of intrinsic charge modulations further exhibits chiral anisotropy with unusual magnetic field response. Theoretical analysis of our experiments suggests a tantalizing unconventional chiral charge density wave in the frustrated kagome lattice, which can not only lead to a large anomalous Hall effect with orbital magnetism, but also be a precursor of unconventional superconductivity.
An unconventional chiral charge order is observed in a kagome superconductor by scanning tunnelling microscopy. This charge order has unusual magnetic tunability and intertwines with electronic topology.
Journal Article