Laboratory Analysis of Debris Flow Characteristics and Berm Performance

In this study, laboratory tests were used to determine the deposition characteristics (runout distance, lateral width, and deposition area) of debris flow and their relationships with the flow characteristics (flow velocity and flow depth) according to the presence of a berm. An experimental flume 1.3 to 1.9 m long, 0.15 m wide, and 0.3 m high was employed to investigate the effects of channel slope and volumetric concentration of sediment with and without the berm. The runout distance (0.201–1.423 m), lateral width (0.045–0.519 m), and deposition area (0.008–0.519 m2) increased as the channel slope increased and as the volumetric concentration of sediment decreased. These quantities also increased with the flow velocity and flow depth. In addition, the maximum reductions in the runout distance, lateral width, and deposition area were 69.1%, 65.9%, and 93%, respectively, upon berm installation. The results of this study illustrate general debris flow characteristics according to berm installation; the reported relationship magnitudes are specific to the experimental conditions described herein. However, the results of this study contribute to the design of site-specific berms in the future by providing data describing the utility and function of berms in mitigating debris flow.

Jet propagation in expanding medium for gamma-ray bursts

ABSTRACT The binary neutron star (BNS) merger event GW170817 clearly shows that a BNS merger launches a short gamma-ray burst (sGRB) jet. Unlike collapsars, where the ambient medium is static, in BNS mergers the jet propagates through the merger ejecta that is expanding outward at substantial velocities (∼0.2c). Here, we present semi-analytical and analytical models to solve the propagation of GRB jets through their surrounding media. These models improve our previous model by including the jet collimation by the cocoon self-consistently. We also perform a series of 2D numerical simulations of jet propagation in BNS mergers and in collapsars to test our models. Our models are consistent with numerical simulations in every aspect (the jet head radius, the cocoon’s lateral width, the jet opening angle including collimation, the cocoon pressure, and the jet–cocoon morphology). The energy composition of the cocoon is found to be different depending on whether the ambient medium is expanding or not; in the case of BNS merger jets, the cocoon energy is dominated by kinetic energy, while it is dominated by internal energy in collapsars. Our model will be useful for estimating electromagnetic counterparts to gravitational waves.

Ultrasound DMAS Beamforming for Estimation of Tissue Speed of Sound in Multi-Angle Plane-Wave Imaging

Various methods have been proposed to estimate the tissue speed of sound (SOS) of propagating medium using the curvature of received channel waveform or the analysis of resultant image quality. In our previous study, baseband delay-multiply-and-sum (DMAS) beamforming methods have been developed for multi-angle plane-wave (PW) imaging which relies on signal coherence among transmit events (Tx-DMAS) or receive channel (Rx-DMAS) or both (2D-DMAS) to suppress low-coherence clutters. In this study, we further extend our DMAS beamforming to quantify the level of signal coherence for determining the average SOS in multi-angle PW imaging. The signal coherence in multi-angle PW imaging is represented as the DMAS coherence factor (DCF) which can be easily estimated from the magnitude ratio of the pixel value of DMAS image to that of DAS image. By searching the beamforming velocity that provides the highest signal coherence of echo matrix, the average tissue SOS of the imaged object can be determined. For the PICMUS experimental dataset, the optimal beamforming velocity (Copt) estimated by the proposed DCF method does provide the best image quality. For the Prodigy dataset, the estimated tissue SOS is 1426 ± 6 m/s which is very close to the actual tissue SOS of 1427 m/s and the estimated SOS also corresponds to the Copt with the minimal −6-dB lateral width and the maximal contrast within an error of 10 m/s. Estimation of tissue SOS in the proposed DCF method is also robust even in the presence of transmit delay error due to deviation of SOS.

Distribution of root system of hop plants in hop gardens with regular rows cultivation

Spatial distribution of the root system of hop (Humulus lupulus L.) in the soil profile is a less explored issue. However, it is known that it can play an important role in the development of new tillage technologies, fertilisation and irrigation, including the use of precision farming principles. In the period from 2015 to 2018, the distribution of the hop root system was evaluated on twelve hop plants of five Czech hop cultivars. The age of the plants ranged from 3 to 15 years. The evaluation took place in the Saaz region at regularly cultivated hop gardens. As part of the evaluation, the root systems of hop plants were removed from the soil profile and subsequently spatially reconstructed. With the help of infrared image analysis, the root intensity in the soil profile and the morphology of the root systems were determined. The root depth of the plants ranged from 1 m to 2.25 m. The lateral width of the hop root system ranged from 0.6 m to 1.5 m. As a result of the rows cultivation, the lateral development of the roots in the upper soil layers was limited. The results were confirmed using the infrared image analysis method to specify the distribution of the root system and the root density of hop plants in the soil profile.

Detecting 1-D and 2-D ground resonances with a single-station approach

SUMMARY The vibration modes of the ground have been described both in the 1-D and 2-D case. The 1-D resonance is found on geological structures whose aspect ratio is low, that is on layers with a lateral width much larger than their thickness. A typical example is that of a horizontal soft sediment layer overlying hard bedrock. In this case, the 1-D resonance frequency, traditionally detected by means of the microtremor H/V (horizontal to vertical spectral ratio) technique, depends on the bedrock depth and on the shear wave velocity of the resonating cover layer. The H/V technique is thus used both to map the resonance frequencies in seismic microzonation studies and for stratigraphic imaging. When 2-D resonance occurs, generally on deep and narrow valleys, the whole sedimentary infill vibrates at the same frequency and stratigraphic imaging can no longer be performed by means of the 1-D resonance equation. Understanding the 1-D or 2-D resonance nature of a site is therefore mandatory to avoid wrong stratigraphic and dynamic interpretations, which is in turn extremely relevant for seismic site response assessment. In this paper, we suggest a procedure to address this issue using single-station approaches, which are much more common compared to the multistation synchronized approach presented by research teams in earlier descriptions of the 2-D resonances. We apply the procedure to the Bolzano sedimentary basin in Northern Italy, which lies at the junction of three valleys, for which we observed respectively 1-D-only, 1-D and 2-D, and 2-D-only resonances. We conclude by proposing a workflow scheme to conduct experimental measurements and data analysis in order to assess the 1-D or 2-D resonance nature of a site using a single-station approach.

Volcanología y geocronología de extensos flujos basálticos neógeno cuaternarios del sureste de Payenia, centro-oeste de Argentina

The basaltic lava flows located in the southeast of Payenia Volcanic Province, Argentina, show lengths between 40 and 181 km. These flows have transversal sections characterized by external vesicular crusts that surround a massive core hosting vesiculated structures. These characteristics defined them as P-type pahoehoe flows. Based on their surface topography, 2 types of flows were determined: sheet flows and hummocky flows. The first were emplaced through inflation and lateral coalescence of lobes in the front of the flow, giving rise to flat roofs and large lateral width. The second ones exhibit a microrelief given by local inflation structures (e.g., tumuli). It is proposed that the lava flows were initially emplaced as sheet flows on low angle slopes (

Sagittal diffusion-weighted imaging in preventing the false-negative diagnosis of acute brainstem infarction: Confirmation of the benefit by anatomical characterization of false-negative lesions

Background: In some cases of acute brainstem infarction (BI), standard axial diffusion-weighted imaging (DWI) does not show a lesion, leading to false-negative (FN) diagnoses. It is important to recognize acute BI accurately and promptly to initiate therapy as soon as possible. Methods: Of the 171 patients with acute cerebral infarctions in our institution who were examined, 16 were diagnosed with true-positive BI (TP-BI) and six with FN-BI. We evaluated the effectiveness of sagittal DWI in accurately diagnosing acute BI and sought to find the cause of its effectiveness by the anatomical characterization of FN-BIs. Results: Considering the direction of the brainstem perforating arteries, we supposed that sagittal DWI might more effectively detect BIs than axial DWI. We found that sagittal DWI detected all FN-BIs more clearly than axial DWI. The mean time between the onset of symptoms and initial DWI was significantly longer in the TP group (17.6 ± 5.5 h) than in the FN group (5.0 ± 1.2 h; P < 0.0001). The lesion volumes were much smaller in FN-BIs (259 ± 82 mm3) than in TP-BIs (2779 ± 767 mm3; P = 0.0007). FN-BIs had a significant inverse correlation with the ventrodorsal length of infarcts (FN 3.5 ± 1.1 mm, TP 11.4 ± 3.6 mm; P < 0.0004) and no correlation with other size parameters such as rostrocaudal thickness and lateral width. Conclusion: Anatomical characterization clearly confirmed that the addition of sagittal DWI to the initial axial DWI in suspected cases of BI ensures its accurate diagnosis and improves the patient’s prognosis.

Investigation of Wheelhouse Flow Interaction and the Influence of Lateral Wheel Displacement

The aim of this research was to improve the understanding of the complex flow featuresfound around a wheel and wheelhouse and to examine how the lateral displacement of the wheelaffects these features and the production of exhibited pressures and forces. A bespoke rotatingwheel rig and accompanying wheelhouse with a fully-pressure-tapped wheel arch was designedand manufactured at Loughborough University. Wind tunnel tests were performed where force andpressure measurements and Particle Image Velocimetry (PIV) data were obtained. The experimentaldata was used to validate unsteady CFD predictions where a k-! SST Improved Delayed DetachedEddy Simulation (IDDES) turbulence model was used in STAR-CCM+ (10.04.009, Siemens). The CFDshowed good agreement with all trends of the experimental results providing a validated numericalmethodology. For both methodologies, a lower amount of wheelhouse drag was found generatedwhen the wheel was rotating. However, the CFD showed that whilst this was the case, totalconfiguration drag had increased. This was attributed to an increase of the wheel and axle drag,illustrated by the change in separation over the wheel itself when located within a wheelhouseand so overcompensating the reduction in body and stand drag. Differences in vortex locationswhen comparing to previously-attained results were due to differences in housing geometry, suchas blockage in the cavity or housing dimensions. Experimental and computational results showedthat up until a 10 mm displacement outboard of the housing, overall drag decreased. The reductionin housing drag was credited to a reduction in the size of outboard longitudinal vortex structures.This led to the lateral width of the shear layer across the housing side being narrower. Overall, thisstudy identified that there were potential benefits to be gained when offsetting a wheel outboard ofthe longitudinal edge of a model housing.

Weight-bearing anteroposterior radiograph of the ankle underestimates the severity of osteoarthritis when there is anterior subluxation of the talus

Category: Ankle Arthritis Introduction/Purpose: On weight-bearing lateral radiograph, anterior aspect of the ankle shows more narrowing than posterior aspect in the ankle osteoarthritis with anterior subluxation of the talus. However, weight-bearing anteroposterior radiograph of the ankle osteoarthritis with anterior subluxation of the talus often shows less severe joint space narrowing than the joint space in the narrowest anterior aspect of the ankle joint. (Fig.1). The purposes of this study were to compare the degree and shape of joint space narrowing in the anterior, middle and posterior aspect of the ankle by using weight-bearing CT and to investigate which area of the ankle was shown on plain weight-bearing ankle anteroposterior radiograph in the ankle osteoarthritis with anterior subluxation of the talus. Methods: We retrospectively evaluated patients who underwent surgery for ankle osteoarthritis in our clinic from January, 2017 to May, 2017. We included patients who showed ankle osteoarthritis with anterior subluxation of the talus in weight-bearing lateral radiograph. We determined anterior, posterior and middle coronal images in sagittal image of the weight-bearing CT.(Fig.1) Talar tilt, medial width of superior clear space(SCS), lateral width of SCS, width of medial clear space and obliteration ratio were measured on plain weight-bearing anteroposterior ankle radiograph, and the three coronal images. The obliteration ratio was obtained by obliteration-width / talus-width * 100.(Fig.1) The radiographic parameters of the anterior coronal image were compared with those on the middle and the posterior coronal image by using paired T-test. The intraclass coefficient was used to investigate which of the three coronal images showed best match with degree and shape of ankle osteoarthritis on the plain weight-bearing ankle anteroposterior radiograph Results: Seventy-one ankles from 71 patients were included in this study. The average age of patients in this study was 62.6 years (range: 19-82). The talar tilt on the anterior coronal image was significantly lower than that on the middle and posterior coronal images. The lateral width of SCS and the width of medial clear space on the anterior coronal image was significantly narrower than those on the middle and the posterior coronal image. The obliteration ratio on the anterior coronal image was significantly higher than that of the middle and the posterior coronal images (Fig.2). The intraclass coefficients indicated that the radiographic parameters on plain weight-bearing anteroposterior radiograph was most reliable with those on the middle coronal image among the three coronal images. Conclusion: Anterior area of ankle shows the most severe osteoarthritis and plain weight-bearing anteroposterior radiograph shows the best match to the middle portion of the ankle, when ankle osteoarthritis has anterior subluxation of the talus. Because middle area of ankle has less severe ankle osteoarthritis than anterior area of ankle in that kind of ankle osteoarthritis, plain weight-bearing radiograph may underestimate the severity of ankle osteoarthritis.