ARST: Auto-Regressive Surgical Transformer for Phase Recognition from Laparoscopic Videos

Phase recognition plays an essential role for surgical workflow analysis in computer assisted intervention. Transformer, originally proposed for sequential data modeling in natural language processing, has been successfully applied to surgical phase recognition. Existing works based on transformer mainly focus on modeling attention dependency, without introducing auto-regression. In this work, an Auto-Regressive Surgical Transformer, referred as ARST, is first proposed for on-line surgical phase recognition from laparoscopic videos, modeling the inter-phase correlation implicitly by conditional probability distribution. To reduce inference bias and to enhance phase consistency, we further develop a consistency constraint inference strategy based on auto-regression. We conduct comprehensive validations on a well-known public dataset Cholec80. Experimental results show that our method outperforms the state-of-the-art methods both quantitatively and qualitatively, and achieves an inference rate of 66 frames per second (fps).Comment: 11 Pages, 3 figure

Cancer Stem Cells and Immunosuppressive Microenvironment in Glioma

Glioma is one of the most common malignant tumors of the central nervous system and is characterized by extensive infiltrative growth, neovascularization, and resistance to various combined therapies. In addition to heterogenous populations of tumor cells, the glioma stem cells (GSCs) and other nontumor cells present in the glioma microenvironment serve as critical regulators of tumor progression and recurrence. In this review, we discuss the role of several resident or peripheral factors with distinct tumor-promoting features and their dynamic interactions in the development of glioma. Localized antitumor factors could be silenced or even converted to suppressive phenotypes, due to stemness-related cell reprogramming and immunosuppressive mediators in glioma-derived microenvironment. Furthermore, we summarize the latest knowledge on GSCs and key microenvironment components, and discuss the emerging immunotherapeutic strategies to cure this disease

Interaction of MSE Abutments with Bridge Superstructures under Seismic Loading \u2013 Shaking Table Tests

65A0556This report presents results from shaking table tests on half-scale mechanically-stabilized earth (MSE) bridge abutments. The testing program consists of five tests where the direction of shaking is in the longitudinal direction of the bridge beam, and one test where the direction of shaking is perpendicular to the bridge beam. The longitudinal shaking tests include a baseline configuration and a parametric study of different configurations to investigate the effects of bridge surcharge stress, reinforcement spacing, reinforcement stiffness, and steel reinforcement on the seismic response of MSE bridge abutments. Experimental design of the scale model followed established similitude relationships for shaking table testing in a 1g gravitational field, including scaling for of geometry, reinforcement stiffness, backfill soil modulus, bridge surcharge stress, and characteristics of the earthquake motions. Facing displacements, bridge seat settlements, accelerations, vertical and lateral stresses, reinforcement strains, and contact forces between the bridge beam and bridge seat were measured for different instrumented sections to evaluate the three-dimensional dynamic response during a series of applied shaking motions. Results indicate that reinforcement spacing and reinforcement stiffness have the most significant effects on the facing displacements and bridge seat settlements for dynamic loading conditions

Seismic Compression of Unsaturated Sand under Different Drainage Conditions

Seismic compression is defined as the accrual of contractive volumetric strains in soils during earthquake shaking and has been recognized as a major cause of seismically induced damage to geotechnical infrastructure. Seismic compression is challenging to predict for unsaturated soils, which are widely encountered in engineered geostructures like embankments or retaining walls involving compacted backfills and in near-surface natural soil layers. This study involves development of a new experimental setup and methodology to characterize the volumetric contraction of unsaturated sands during cyclic shearing under different drainage conditions. Specifically, a new cyclic simple shear device with suction-saturation control and embedded pore air and water pressure sensors was developed to perform cyclic shearing tests on unsaturated sand specimens with different initial suctions in drained, partially drained, or undrained conditions. This device can measure the changes in volumetric strain, degree of saturation, and pore air and water pressures, which can help in characterizing the evolution in effective stress and hydromechanical coupling effects during cyclic shearing. The device also permits evaluation of the shear modulus and damping ratio for cyclic shear strain amplitudes ranging from 0.1 to 10%.Sand specimens under nearly-saturated, dry and unsaturated conditions in the funicular regime of the SWRC were assessed using the new cyclic simple shear device under different drainage conditions. During drained cyclic shearing (constant suction), volumetric strains caused a shift in the soil-water retention curves to higher degrees of saturation. This led to a greater effective stress for the same matric suction and enhanced the resistance of unsaturated specimens to seismic compression. The stabilized volumetric strain after drained cyclic shearing followed a log-linear relationship with matric suction. During undrained cyclic shearing, seismic compression volumetric strains followed a nonlinear relation with degree of saturation. In addition to the initial volume of pore air, the evolution in mean effective stress resulting from hydromechanical coupling played a significant role on the magnitude of seismic compression during undrained cyclic shearing. The pore air and water pressures were found to both increase but at different rates, leading to a decrease in matric suction and effective stress. In both drained and undrained cyclic shearing, the shear modulus was found to increase due to seismic compression. The data from this study confirm the usefulness of the new device and were used to form the basis for a new constitutive soil model for cyclic shearing of unsaturated sand

Seismic Compression of Unsaturated Sand under Different Drainage Conditions

Seismic compression is defined as the accrual of contractive volumetric strains in soils during earthquake shaking and has been recognized as a major cause of seismically induced damage to geotechnical infrastructure. Seismic compression is challenging to predict for unsaturated soils, which are widely encountered in engineered geostructures like embankments or retaining walls involving compacted backfills and in near-surface natural soil layers. This study involves development of a new experimental setup and methodology to characterize the volumetric contraction of unsaturated sands during cyclic shearing under different drainage conditions. Specifically, a new cyclic simple shear device with suction-saturation control and embedded pore air and water pressure sensors was developed to perform cyclic shearing tests on unsaturated sand specimens with different initial suctions in drained, partially drained, or undrained conditions. This device can measure the changes in volumetric strain, degree of saturation, and pore air and water pressures, which can help in characterizing the evolution in effective stress and hydromechanical coupling effects during cyclic shearing. The device also permits evaluation of the shear modulus and damping ratio for cyclic shear strain amplitudes ranging from 0.1 to 10%.Sand specimens under nearly-saturated, dry and unsaturated conditions in the funicular regime of the SWRC were assessed using the new cyclic simple shear device under different drainage conditions. During drained cyclic shearing (constant suction), volumetric strains caused a shift in the soil-water retention curves to higher degrees of saturation. This led to a greater effective stress for the same matric suction and enhanced the resistance of unsaturated specimens to seismic compression. The stabilized volumetric strain after drained cyclic shearing followed a log-linear relationship with matric suction. During undrained cyclic shearing, seismic compression volumetric strains followed a nonlinear relation with degree of saturation. In addition to the initial volume of pore air, the evolution in mean effective stress resulting from hydromechanical coupling played a significant role on the magnitude of seismic compression during undrained cyclic shearing. The pore air and water pressures were found to both increase but at different rates, leading to a decrease in matric suction and effective stress. In both drained and undrained cyclic shearing, the shear modulus was found to increase due to seismic compression. The data from this study confirm the usefulness of the new device and were used to form the basis for a new constitutive soil model for cyclic shearing of unsaturated sand