Leveling the Workload for Radiologists in Diagnostic Mammography: Application of Lean Principles and Heijunka

To facilitate the delivery of accurate and timely care to patients in complex environments, process improvement methodologies such as Lean can be very effective. Lean is a quality improvement methodology that seeks to add value for patients and employees by continuously improving processes and eliminating waste. At our institution, Lean principles were applied to improve efficiency and minimize waste in the diagnostic breast imaging reading room. This paper describes how we applied Lean principles, including plan-do-study-act testing, level-loading (heijunka), and visual management, to level the workload of the diagnostic radiologists in our practice. Implementation of these principles to improve the diagnostic workflow in breast imaging is described along with examples from our practice, including challenges and future opportunities.

Centralized Ambulance Destination Determination: A Retrospective Data Analysis to Determine Impact on EMS System Distribution, Surge Events, and Diversion Status

Introduction: Emergency medical services (EMS) systems can become impacted by sudden surges that can occur throughout the day, as well as by natural disasters and the current pandemic. Because of this, emergency department crowding and ambulance “bunching,” or surges in ambulance-transported patients at receiving hospitals, can have a detrimental effect on patient care and financial implications for an EMS system. The Centralized Ambulance Destination Determination (CAD-D) project was initially created as a pilot project to look at the impact of an active, online base hospital physician and paramedic supervisor to direct patient destination and distribution, as a way to improve ambulance distribution, decrease surges at hospitals, and decrease diversion status. Methods: The project was initiated March 17, 2020, with a six-week baseline period; it had three additional study phases where the CAD-D was recommended (Phase 1), mandatory (Phase 2), and modified (Phase 3), respectively. We used coefficients of variation (CV) statistical analysis to measure the relative variability between datasets (eg, CAD-D phases), with a lower variation showing better and more even distribution across the different hospitals. We used analysis of co-variability for the CV to determine whether level loading was improved systemwide across the three phases against the baseline period. The primary outcomes of this study were the following: to determine the impact of ambulance distribution across a geographical area by using the CV; to determine whether there was a decrease in surge rates at the busiest hospital in this area; and the effects on diversion. Results: We calculated the CV of all ratios and used them as a measure of EMS patient distribution among hospitals. Mean CV was lower in Phase 2 as compared to baseline (1.56 vs 0.80 P < 0.05), and to baseline and Phase 3 (1.56 vs. 0.93, P <0.05). A lower CV indicates better distribution across more hospitals, instead of the EMS transports bunching at a few hospitals. Furthermore, the proportion of surge events was shown to be lower between baseline and Phase 1 (1.43 vs 0.77, P <0.05), baseline and Phase 2 (1.43 vs. 0.33, P < 0.05), and baseline and Phase 3 (1.43 vs 0.42, P < 0.05). Diversion was shown to increase over the system as a whole, despite decreased diversion rates at the busiest hospital in the system. Conclusion: In this retrospective study, we found that ambulance distribution increased across the system with the implementation of CAD-D, leading to better level loading. The surge rates decreased at some of the most impacted hospitals, while the rates of hospitals going on diversion paradoxically increased overall. Specifically, the results of this study showed that there was an improvement when comparing the CAD-D implementation vs the baseline period for both the ambulance distribution across the system (level loading/CV), and for surge events at three of the busiest hospitals in the system.

Laboratory Study On Mechanical Response And Failure Mechanism of Red-Bed Soft Rock Under Water-Rock Interaction

Red-bed soft rock is a geomaterial that displays special deformation and failure characteristics. The stability of red-bed slopes can be negatively impacted by water and stepped excavation disturbance; however, there is limited research regarding the mechanical behavior and failure characteristics of red-bed soft rock under the action of water-rock hydro-mechanical coupling. In this study, to explore the mechanical response and failure mechanisms of red-bed soft rock under coupled water-rock hydro-mechanical action, a visual experimental platform based on digital radiography and a multi-level loading device was constructed. Angiography was used to visualize the rock fracture process by replacing fissure water with a contrast medium. Multi-level loading was applied to cubic red-bed mudstone samples, and acoustic emission signals, stress, flow rate, and digital radiography images were collected during the failure process. An original image processing method based on Hough transform and a convolutional neural network was used to segment and extract cracks from the imagery, and fissure water flow characteristics, rock mechanical response, and crack evolution were analyzed in detail (Liu et al., 2015; Lv et al., 2013, 2014). Results showed that when the Felicity ratio FR was lower than 1.2, water could induce secondary "water-damaged cracks" in the red-bed samples. Study findings were used to highlight the importance of improved early-warning methods for rainfall-induced landslides at an engineering scale. The original experimental platform proposed and evaluated in this study provides a new and powerful tool to investigate the mechanical behavior of different rock types under the action of water-rock hydro-mechanical coupling at a laboratory scale. These findings will facilitate improved disaster prevention strategies for red-bed geological bodies.

Cyclic loading regime considered beneficial does not protect injured and interleukin-1-inflamed cartilage from post-traumatic osteoarthritis

Post-traumatic osteoarthritis is a degenerative musculoskeletal condition where homeostasis of articular cartilage is perturbated by lesions and inflammation, leading to abnormal tissue-level loading. These mechanisms have rarely been included simultaneously in in vitro osteoarthritis models. We modeled the early disease progression in bovine cartilage regulated by the coaction of (1) mechanical injury, (2) pro-inflammatory interleukin-1α challenge, and (3) cyclic loading mimicking walking and considered beneficial (15% strain, 1 Hz). Surprisingly, cyclic loading did not protect cartilage from accelerated glycosaminoglycan loss over 12 days of interleukin-1-culture despite promoting aggrecan biosynthesis. Our time-dependent data suggest that this loading regime could be beneficial in the first days following injury but later turn detrimental in interleukin-1-inflamed cartilage. Consequently, early anti-catabolic drug intervention may inhibit, whereas cyclic loading during chronic inflammation may promote osteoarthritis progression. Our data on the early stages of post-traumatic osteoarthritis could be utilized in the development of countermeasures for disease progression.

SHEAR STRAINS AT SERVICE LOAD CONDITIONS IN CRACKED REINFORCED CONCRETE ELEMENTS SUBJECTED TO SHEAR

The contribution of the shear strains to the overall deformations of reinforced concrete (RC) elements is typically neglected. However, when RC cracks in shear, its shear modulus is significantly reduced, and the contribution of the shear strains to the overall deformations of the elements is increased. Experimental testing has shown that shear deformations can be significant. Under service conditions, RC can be cracked in shear and hence, a simple method for the calculation of the effective cracked shear modulus is desired. Research has shown that the part of the shear response after cracking and before yielding can be well modeled using a straight line. This paper uses existing experimental data and the equations of the modified compression field theory (MCFT) to examine this part of the response in RC membrane elements and to develop two simple equations that can be used to characterize the straight line. The proposed equations are evaluated by comparing their results with existing experimental data on the shear response of thin RC membrane elements. The comparison includes the post-cracking response and the shear strains at estimated service level loading. A very good agreement is obtained between the experimental and the calculated results. The simplicity of the proposed equations is illustrated using a numerical example.

The effect of seismic-like induced cyclic loading on damage response of sandstone and granite

&lt;p&gt;The detailed study of rock response to cyclic loading induced by natural phenomena, such as seismic and volcanic activities, and man-made explosions and excavation is necessary for failure prediction and hazard mitigation. The effect of the maximum stress level, loading amplitude, and frequency of stress cycles on the fatigue life and failure mechanisms of two microstructurally different rocks of granite/granodiorite and sandstone is investigated. Test data obtained from comprehensive experiments conducted on these rock types incorporated with the results of previous studies show that the fatigue life time of both rock types increases with a decrease in either maximum stress level or stress amplitude. Nevertheless, the fatigue strength threshold of hard rocks like granite is generally lower than that of soft rocks like sandstone. The study also shows that the low-frequency cyclic loading has more damaging effect on both rock types than the high frequency loading. This investigation demonstrates that the failure mechanism of rocks under cyclic loading is characterized by the development of more tensile microcracks compared to the monotonic loading and the opening and extension of the axial tensile microfractures are more evident at higher maximum stresses or loading amplitudes or at lower loading frequencies. The results presented in this study will contribute to a deeper understanding of the fatigue responses of sandstone and granite to seismic-generated loading&amp;#8211;unloading processes under different conditions of stress cycles.&lt;/p&gt;

Annual sea level variations in the Red Sea observed using GNSS

SUMMARY Annual sea level variations in the Red Sea have amplitudes of 15–20 cm as observed using various techniques such as tide gauges, satellite altimetry and recently Gravity Recovery and Climate Experiment (GRACE) satellite data. In this study, we demonstrate that Global Navigation Satellite System (GNSS) observations can also be used to measure the effect of these sea level variations. The extra water mass presses on the seafloor, which causes horizontal and vertical deformations. Using time-series from 10 coastal GNSS stations, we observe annual horizontal and vertical loading displacements with amplitudes of 2–5 mm. When correcting for atmospheric, hydrological and surface water loading and a residual geocentre motion, significant annual signals of approximately 0.5 and 2 mm are still observed for the horizontal and vertical components, respectively. In the northern Red Sea, the observed annual signals and predicted annual sea level loading show good agreement. This confirms that the signal is mostly a result of the variations in water mass and thermal expansion. Furthermore, we conclude that the uncertainties in the hydrological model over Ethiopia and Eritrea influence the loading over the southern Red Sea, which was underestimated in previous studies using GRACE data.

An Investigation on the Viscoelastic Behavior of Eggshell Membrane by Nanoindentation Technology

The mechanical properties of eggshell membrane (ESM) are comparable to those of human patellar tendon or skin. This paper, based on static and dynamic nanoindentation technique, studied the time-dependent behavior, i.e., creep and relaxation of the ESM. The effect of loading level, loading rate and holding time on viscoelastic behavior were discussed by using the static measurement method of nanoindentation. The storage modulus, loss modulus and loss factor were obtained as a function of frequency. It was found that the outer membrane (OM) exhibits more apparent relaxation properties and stronger capacity to resist creep deformation than that of the inner membrane (IM). In addition, the loss factor of the IM is larger than that of the OM which caused a larger viscous damping of IM. This work can contribute to the bioinspired applications of ESM.