A Comparison of the Distortion in the Same Field MRI and MR-Linac System With a 3D Printed Phantom

PurposeA 3D printed geometric phantom was developed that can be scanned with computed tomography (CT) and magnetic resonance imaging (MRI) to measure the geometric distortion and determine the relevant dose changes.Materials and MethodsA self-designed 3D printed photosensitive resin phantom was used, which adopts grid-like structures and has 822 1 cm2 squares. The scanning plan was delivered by three MRI scanners: the Elekta Unity MR-Linac 1.5T, GE Signa HDe 1.5T, and GE Discovery-sim 750 3.0T. The geometric distortion comparison was concentrated on two 1.5T MRI systems, whereas the 3.0T MRI was used as a supplemental experiment. The most central transverse images in each dataset were selected to demonstrate the plane distortion. Some mark points were selected to analyze the distortion in the 3D direction based on the plane geometric distortion. A treatment plan was created with the off-line Monaco system.ResultsThe distortion increases gradually from the center to the outside. The distortion range is 0.79 ± 0.40 mm for the Unity, 1.31 ± 0.56 mm for the GE Signa HDe, and 2.82 ± 1.48 mm for the GE Discovery-sim 750. Additionally, the geometric distortion slightly affects the actual planning dose of the radiotherapy.ConclusionGeometric distortion increases gradually from the center to the outside. The distortion values of the Unity were smaller than those of the GE Signa HDe, and the Unity has the smallest geometric distortion. Finally, the Unity’s dose variation best matched with the standard treatment plan.

How Do I Compare? The Effect of Work-Unit Demographics on Reactions to Pay Inequality

Prior research suggests that individuals react negatively when they perceive they are underpaid. Moreover, individuals frequently select pay referents who share their race and gender, suggesting that demographic similarity affects one’s knowledge of pay differences. Leveraging these insights, the authors examine whether the gender and racial composition of a work unit shapes individuals’ reactions to pay deprivation. Using field data from a large health care organization, they find that pay deprivation resulting from workers receiving less pay than their same-sex and same-race coworkers prompts a significantly stronger response than does pay deprivation arising from workers receiving less pay than their demographically dissimilar colleagues. A supplemental experiment reveals that this relationship likely results from individuals’ propensity to select same-category others as pay referents, shaping workers’ information about their colleagues’ pay. The study’s findings underscore the need to theoretically and empirically account for how demographically driven social comparison processes affect reactions to pay inequality.

Destigmatization and Its Imbalanced Effects in Labor Markets

Destigmatization is an understudied social process in which the negative outcomes for a previously stigmatized group improve. We theorize that during a period of destigmatization, the effects of stigma persist more strongly for people stigmatized by association than for those directly stigmatized. We propose that this occurs because, during periods of destigmatization, conscious prejudice has diminished but nonconscious prejudice remains, so people correct for their explicit biases toward individuals with the stigmatizing trait but are unaware of their ongoing implicit prejudice toward those stigmatized by association. Our evidence comes from archival data on individual employment in film during the cold war years in Hollywood. It shows that as the stigma of being on an anticommunist blacklist weakened, the employment penalty for being a coworker of a blacklisted artist was greater than the penalty for actually having been on the blacklist itself. A supplemental experiment, designed to address the limitations of archival data, shows the same imbalanced employment penalties in another stigma currently undergoing destigmatization (that of physical disability). Paradoxically, as stigmas recede, harmful effects persist more for associates of stigmatized individuals than for the stigmatized themselves. This paper was accepted by David Simchi-Levi, organizations.

Effects of Servo Tensile Test Parameters on Mechanical Properties of Medium-Mn Steel

As a new type of third-generation automotive steel with high strength and plasticity, medium-Mn steel (MMnS) has been widely used in automotive industries for its excellent properties. In recent years, servo stamping technology for high-strength metal forming is a hot topic due to its good performance in forming under complex processing conditions, and servo parameters determine the forming quality. In this paper, experiments considering tensile speed and position where speed changes (PSC) were carried out on MMnS to investigate the influences of tensile parameters on mechanical properties including strength and total elongation (TE). The results show that PSC does not significantly impact total elongation. Initial tensile speed (ITS) and final tensile speed (FTS) significantly impact the total elongation. The interaction between all tensile parameters can impact total elongation. Two artificial neural networks, back propagation neural network (BPNN) and radial basis function neural network (RBFNN), were used to establish analytical models. The results of supplemental experiment and residual analysis were conducted to verify the accuracy of the analytical models. The BPNN has a better performance and the analytical model shows that with the increase of PSC, it has a slight impact on the changes of optimal and minimum total elongation, but the combinations of tensile parameters to obtain total elongations higher than 40% change significantly.

Cut of Clothes Maximizes the Effect of Amodal Completion to Make You Look Thinner

Amodal completion has various functional effects, including an apparent slimming effect achieved by clothes. Local and global completion factors have been examined in previous studies, which also apply to the apparent slimming effect. Exposed parts of the body constitute the local factor at the junction area, while the shape or cut of the clothes is concerned with the whole configuration. This study investigated which is more important, the local or whole factors, for amodal completion in relation to the apparent slimming effect using drawings as stimuli. In Experiment 1, we examined the effects of the length and cut of a skirt. The length of the skirt corresponds to the local factor of the body, that is, the legs, because the exposed parts of the legs depend on skirt length (assuming a person of consistent height). We found that skirts' cut influenced their effect more than their length did. Experiments 2 and 3 revealed that the vertical form of clothes affects slimming by hiding thicker parts of the body and highlighting thinner parts. A supplemental experiment using geometrical figures suggested that the apparent slimming effect of clothes might occur only in the human body configuration.

Promotion, Relative Performance Information, and the Peter Principle

ABSTRACT I examine the effects of providing workers with relative performance information (RPI) on employers' promotion decisions and the impact of those decisions on worker performance. In my experimental setting, the job after promotion requires higher-level abilities than the current job. I find that workers increase their effort to improve their current job performance after a promotion opportunity is announced because they expect this to increase their chances of promotion, even though the new task requires higher-level abilities. Moreover, because employers anticipate that workers who have RPI will react negatively if they see that the best current job performer is not promoted, employers promote the best current job performer, rather than the worker best suited for the next job, more often when workers have RPI than when they do not. Consistent with the Peter Principle, I find that when workers have RPI, the promoted worker's performance is lower after promotion because the promoted worker lacks the ability to perform the new job well. Finally, in a supplemental experiment, I find that providing workers with feedback on their abilities to perform the next job, in addition to current job RPI, improves the effective sorting of workers, but it comes at the cost of reduced promotion-based incentives. My results suggest that, notwithstanding the benefits documented in previous studies, RPI also imposes potential costs that firms should take into account when deciding whether to provide workers with RPI. JEL Classifications: M41; M51; M52. Data Availability: Contact the author.

Aeration of water with oxygen microbubbles and its purging effect

In this paper, we apply aeration with oxygen microbubbles to tap water; the intent is to quantitatively evaluate whether nitrogen gas originally dissolved in the water under the atmosphere is purged by the aeration with oxygen microbubbles. Oxygen microbubbles are continuously injected into the circulation system of tap water open to the atmosphere. While the concentration of dissolved oxygen (DO) can be detected by a commercial DO meter, that of dissolved nitrogen (DN) is unavailable. To detect the DN level, we observe the growth of millimetre-sized gas bubbles nucleated at glass surfaces in contact with the aerated water and compare it with the multi-species theory of Epstein and Plesset where the (unknown) DN concentration is treated as a fitting parameter. In the theory, we solve binary diffusion of each gas species (oxygen or nitrogen) in the water independently, under the assumption that the dissolved gases are sufficiently dilute. Comparisons between the experiment and the theory suggest that the DN in the water is effectively purged by the oxygen aeration. The supplemental experiment of aeration with nitrogen microbubbles is also documented to show that the DO can be effectively purged as well.

The Effect of Partition Dependence on Assessing Accounting Estimates

SUMMARY When auditors evaluate accounting estimates by testing management's estimation process, both current and proposed guidance call on auditors to review management's consideration of alternative assumptions and outcomes. Using partition dependence theory, a psychological bias that occurs when decision makers review a set of potential outcomes, we hypothesize that management's presentation of alternative estimate outcomes can bias auditors toward a management-preferred estimate. We demonstrate this result in a case-based experiment using senior auditor participants. We also perform two follow-up experiments, using student participants, to rule out competing rationales for our findings. In a final supplemental experiment, we test partition dependence predictions in a risk assessment setting and find results consistent with partition dependence. Our results have audit quality implications and, therefore, should be of interest to both regulators and audit firms. JEL Classifications: M40; M41; M42.