This paper proposes that elastic potentials, which may be rigorously formulated using the negative Gibbs free energy or the complementary strain energy density, may be used as the yield surface of ...elasto-plastic constitutive models. Thus, the yield surface may be assumed in some materials as an elastic potential surface for a specific level of critical complementary strain energy density. Traditional approaches, such as the total strain energy criterion, only consider second order terms, i.e., the elastic potential is centred at the origin of the current stress state. Here, first order terms are considered, and consequently, the elastic potential may be translated, which allows to reproduce the desired level of tension-compression asymmetry. The proposed approach only adds two additional parameters, e.g., uniaxial compressive and tensile yield limits, to the elastic ones. For linear elasticity, the proposed approach provides elliptical yield surfaces and shows a correlation between the shape of the ellipse and the Poisson’s ratio, which agree with published experimental data for soils and metallic glasses. This elliptical yield surface also fits well experimental values of amorphous polymers and some rocks. Besides, the proposed approach automatically considers the influence of the intermediate stress. For non-linear elasticity, a wider range of elastic potentials, i.e., yield surfaces, are possible, such as distorted ellipsoids. For the case of incompressible non-linear materials, the yield surfaces are between von Mises and Tresca ones.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This paper reviews the main modeling techniques for stone columns, both ordinary stone columns and geosynthetic-encased stone columns. The paper tries to encompass the more recent advances and ...recommendations in the topic. Regarding the geometrical model, the main options are the "unit cell", longitudinal gravel trenches in plane strain conditions, cylindrical rings of gravel in axial symmetry conditions, equivalent homogeneous soil with improved properties and three-dimensional models, either a full three-dimensional model or just a three-dimensional row or slice of columns. Some guidelines for obtaining these simplified geometrical models are provided and the particular case of groups of columns under footings is also analyzed. For the latter case, there is a column critical length that is around twice the footing width for non-encased columns in a homogeneous soft soil. In the literature, the column critical length is sometimes given as a function of the column length, which leads to some disparities in its value. Here it is shown that the column critical length mainly depends on the footing dimensions. Some other features related with column modeling are also briefly presented, such as the influence of column installation. Finally, some guidance and recommendations are provided on parameter selection for the study of stone columns.
A review on deep learning in UAV remote sensing Osco, Lucas Prado; Marcato Junior, José; Marques Ramos, Ana Paula ...
International journal of applied earth observation and geoinformation,
October 2021, 2021-10-00, 2021-10-01, Letnik:
102
Journal Article
Recenzirano
Odprti dostop
•Combining deep learning and UAV-based data is an emerging trend in remote sensing.•Most articles published rely on CNN-based methods.•Future perspectives in UAV-based data processing still have much ...to cover.
Deep Neural Networks (DNNs) learn representation from data with an impressive capability, and brought important breakthroughs for processing images, time-series, natural language, audio, video, and many others. In the remote sensing field, surveys and literature revisions specifically involving DNNs algorithms’ applications have been conducted in an attempt to summarize the amount of information produced in its subfields. Recently, Unmanned Aerial Vehicle (UAV)-based applications have dominated aerial sensing research. However, a literature revision that combines both “deep learning” and “UAV remote sensing” thematics has not yet been conducted. The motivation for our work was to present a comprehensive review of the fundamentals of Deep Learning (DL) applied in UAV-based imagery. We focused mainly on describing the classification and regression techniques used in recent applications with UAV-acquired data. For that, a total of 232 papers published in international scientific journal databases was examined. We gathered the published materials and evaluated their characteristics regarding the application, sensor, and technique used. We discuss how DL presents promising results and has the potential for processing tasks associated with UAV-based image data. Lastly, we project future perspectives, commentating on prominent DL paths to be explored in the UAV remote sensing field. This revision consisting of an approach to introduce, commentate, and summarize the state-of-the-art in UAV-based image applications with DNNs algorithms in diverse subfields of remote sensing, grouping it in the environmental, urban, and agricultural contexts.
We have investigated the effect of printing angle and device orientation on the development of high-throughput (HT), self-insulated, 3D printed 3D Microelectrode Arrays (HT-3DMEAs) for in vitro ...biotechnology applications and its repercussions for optical, mechanical, and electrical properties of the final device. Makerspace based development using micro-Stereolithography (<inline-formula> <tex-math notation="LaTeX">\boldsymbol {\mu } </tex-math></inline-formula>SLA) 3D printing and ink casting technique were carried out to develop a 24-well device with self-insulated 3D microelectrodes, with 100% yield and 7 microtowers per well acting as supports for the microelectrodes. These MEAs were further characterized by Optical Microscopy, Electrical Impedance Spectroscopy (EIS), Laser Scanning Confocal Microscopy, Scanning Electron Microscopy (SEM), and UV-Vis Spectroscopy. Surface flatness required for the microelectrode formation was obtained for 0° tilt printed version at top-side orientation. The process optimization and results were interpreted using established <inline-formula> <tex-math notation="LaTeX">\boldsymbol {\mu } </tex-math></inline-formula>SLA theory and COMSOL modeling. Artifact size determination with a maximum 6% error was predicted. Experimental finding on the microelectrode formation, i.e., a potentially useful microbullet shape was observed and confirmed using Laser Confocal and SEM microscopy characterization and COMSOL simulation. These results allow for greater understanding of the device-process relationships for HT-3DMEAs and paves the pathway towards scalability, denser electrodes and even higher well counts for HT screening in biotechnology. 2021-0201
Synapses store information by long-lasting modifications of their structure and molecular composition, but the precise chronology of these changes has not been studied at single-synapse resolution in ...real time. Here we describe the spatiotemporal reorganization of postsynaptic substructures during long-term potentiation (LTP) at individual dendritic spines. Proteins translocated to the spine in four distinct patterns through three sequential phases. In the initial phase, the actin cytoskeleton was rapidly remodeled while active cofilin was massively transported to the spine. In the stabilization phase, cofilin formed a stable complex with F-actin, was persistently retained at the spine, and consolidated spine expansion. In contrast, the postsynaptic density (PSD) was independently remodeled, as PSD scaffolding proteins did not change their amount and localization until a late protein synthesis-dependent third phase. Our findings show how and when spine substructures are remodeled during LTP and explain why synaptic plasticity rules change over time.
•Postsynaptic proteins are reorganized during LTP in three sequential phases•Cofilin is rapidly, persistently enriched in the spine via a stable F-actin complex•Cofilin signaling pathway is necessary for the maintenance of spine expansion•Delayed PSD growth is spine expansion independent but protein synthesis dependent
Bosch et al. describe the spatiotemporal reorganization of postsynaptic substructures during potentiation at single dendritic spines. They uncover the late-phase growth of the postsynaptic density and the unique dynamics of cofilin, which play a critical role in consolidating spine growth.
Este artículo recoge algunos aspectos teóricos recientes relativos a columnas de grava que pueden resultar útiles para su diseño y cálculo. En esta segunda parte, se recogen comentarios sobre la ...estimación del diámetro de las columnas, sobre grupos de columnas, y sobre la problemática específica causada por asientos de consolidación secundaria. Se muestra que el número de columnas mientras se mantenga el área de sustitución bajo la cimentación no tiene influencia en el valor del asiento y que la posición de las columnas dentro de la cimentación tiene una influencia muy pequeña. La longitud crítica de las columnas es del orden de 2 veces el ancho o diámetro de la cimentación superficial. También se muestra la menor eficacia de las columnas de grava en la reducción de asientos por consolidación secundaria. Cuando se estime que los asientos por consolidación secundaria pueden ser importantes, lo recomendable es realizar una sobrecarga.
The essential cytoskeletal protein actin and its functions are paramount for motility, communication, and locomotive processes in eukaryotic cells. Detection and quantification of actin protein is of ...great interest for in vitro studies potentially elucidating unknown cellular mechanisms affecting drug responses with an extension to the study of disease states (e.g., study of neurodegenerative disorders). To this end, development of biomedical platforms and biosensors plays an important role in providing reliable and sensitive devices to study such intracellular constructs. Here, we present for the first time the microfabrication, characterization, testing, and electrical/interfacial modeling of a microfluidic biosensor for actin protein characterization. The device allows for the interaction and characterization of actin bundles using electrochemical impedance spectroscopy (EIS). The device was tested with <inline-formula> <tex-math notation="LaTeX">1 \mu \text{M} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">8 \mu \text{M} </tex-math></inline-formula> actin bundles concentrations producing shifts in impedance response in the significant biological frequency of 1 kHz from 17 to 30 kOhm (<inline-formula> <tex-math notation="LaTeX">\text{k}\Omega </tex-math></inline-formula>). Interfacial capacitance and electrical modeling showed that at increasing actin bundles concentrations, the distance from the electrode to the diffusion region (Debye length) was reduced from 386 to 136, and from 1526 to 539 Å. Interfacial capacitance was evaluated for <inline-formula> <tex-math notation="LaTeX">1 \mu \text{M} </tex-math></inline-formula> concentration at two dielectric constants (<inline-formula> <tex-math notation="LaTeX">\boldsymbol {\varepsilon }_{\mathbf {r}} </tex-math></inline-formula> = 5 and 78) resulting in 3.8 and 15.6 mF/m2 respectively. Similarly, for <inline-formula> <tex-math notation="LaTeX">8 \mu \text{M} </tex-math></inline-formula> concentration, interfacial capacitance resulted in 10.1 and 43.3 mF/m2 for the same values of <inline-formula> <tex-math notation="LaTeX">\boldsymbol {\varepsilon }_{\mathbf {r}} </tex-math></inline-formula>. Based on these theoretical calculations, the interface model could accurately predict the quantification of the actin bundles previously elucidated by the experimental EIS method. 2023-0180
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Intraspinal microstimulation (ISMS) may help to restore motor functions after spinal cord injury. ISMS caudal to the lesion activates motoneurons and evokes selective movements with ...graded force in rats and other mammals. We investigated the safety and effectiveness of conducting polymer (CP)-coated carbon microfibers (CMFs) for ISMS. 7-µm-diameter CMFs coated with poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonic acid)-co-(maleic acid) (PEDOT:PSS-co-MA) were used to apply current-controlled biphasic electric pulses at the cervical spinal cord (C7) of anesthetized rats. Electrode performance and motoneuron activation, as readout by voltage transients, cyclic voltammetry, electrochemical impedance spectroscopy, electromyography (EMG) and foreleg kinematics, were investigated as a function of microfiber length (50 µm vs. 250 µm) and presence of polymer coating. The microfibers were very effective in activating specific spinal motoneurons, with the lowest stimulus thresholds varying between −28 µA and −46 µA in the cathodic phase. EMG and kinematic thresholds decreased when the microfiber tip approached the targeted motor nucleus (triceps brachii, t.b.) from the dorsal spinal cord surface. ISMS with polymer-coated CMFs produced higher electrical activity in the t.b. fascicles compared to bare CMFs. PEDOT:PSS-co-MA coating of 250-µm CMFs avoided the generation of unsafe overvoltages for biphasic pulses up to −80/+40 µA in vivo, although the positive effect of the conducting polymer was lost after the application of a few thousands of electric pulses. Thus, CP-coated CMFs may provide an effective and minimally invasive electrode for ISMS; however, polymer optimization is still required to improve its electrical stability and safety for long-term use.
Statement of significance
Intraspinal microstimulation may restore motor functions after spinal cord injury. In the present study we demonstrate that carbon microfibers (CMFs) coated with the conducting polymer PEDOT:PSS-co-MA can be advantageously used for this purpose. These microfibers allow for both effective and temporarily safe electrical activation of spinal motor circuits with high spatial resolution. The presence of the polymer enhances the effectiveness of the electrical stimuli to recruit spinal motoneurons. Thus, conducting polymer-coated CMFs have potential for the development of advanced neuroprosthetic devices, although further improvements are needed regarding their electrochemical and mechanical stability.
The group of Gram-negative bacteria capable of oxidising ethanol to acetic acid is called acetic acid bacteria (AAB). They are widespread in nature and play an important role in the production of ...food and beverages, such as vinegar and kombucha. The ability to oxidise ethanol to acetic acid also allows the unwanted growth of AAB in other fermented beverages, such as wine, cider, beer and functional and soft beverages, causing an undesirable sour taste. These bacteria are also used in the production of other metabolic products, for example, gluconic acid, l-sorbose and bacterial cellulose, with potential applications in the food and biomedical industries. The classification of AAB into distinct genera has undergone several modifications over the last years, based on morphological, physiological and genetic characteristics. Therefore, this review focuses on the history of taxonomy, biochemical aspects and methods of isolation, identification and quantification of AAB, mainly related to those with important biotechnological applications.
El artículo contiene un estudio sobre el fundamento, el alcance y las consecuencias prácticas del principio de jerarquía normativa en el derecho canónico. La doctrina se ha detenido principalmente en ...la jerarquía entre las normas legales y las normas administrativas. En este trabajo se amplía el estudio a la jerarquía entre normas constitucionales y normas legales. La doctrina entiende habitualmente que las normas que formalizan aspectos de la constitución material son normas constitucionales. Entre ellas se encuentran los derechos fundamentales, último eslabón en el desarrollo del constitucionalismo, secundado también por el Concilio Vaticano II y por la codificación canónica. El autor expone las implicaciones teóricas y técnicas del principio de jerarquía en el sistema normativo, como la sujeción del legislador a las normas constitucionales.
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