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Microstereolithography is capable of producing millimeter-scale polymer parts having micron-scale features. Material properties of the cured polymers can vary depending on build parameters such as exposure. Current techniques for determining the material properties of these polymers are limited to static measurements via micro/nanoindentation, leaving the dynamic response undetermined. The purpose of this paper is to demonstrate a method to measure the dynamic response of additively manufactured parts to infer the dynamic modulus of the material in the ultrasonic range.

Frequency-dependent material parameters, such as the complex Young’s modulus, have been determined for other relaxing materials by measuring the wave speed and attenuation of an ultrasonic pulse traveling through the materials. This work uses laser Doppler velocimetry to measure propagating ultrasonic waves in a solid cylindrical waveguide produced using microstereolithography to determine the frequency-dependent material parameters of the polymer. Because the ultrasonic wavelength is comparable with the part size, a model that accounts for both geometric and viscoelastic dispersive effects is used to determine the material properties using experimental data.

The dynamic modulus in the ultrasonic range of 0.4-1.3 MHz was determined for a microstereolithography part. Results were corroborated by using the same experimental method for an acrylic part with known properties and by evaluating the natural frequency and storage modulus of the same microstereolithography part with a shaker table experiment.

The paper demonstrates a method for determining the dynamic modulus of additively manufactured parts, including relatively small parts fabricated with microstereolithography.

Communications regarding this column should be addressed to Mrs. Cheney, Peabody Library School, Nashville, Tenn. 37203. Mrs. Cheney does not sell the books listed here. They are available through normal trade sources. Mrs. Cheney, being a member of the editorial board of Pierian Press, will not review Pierian Press reference books in this column. Descriptions of Pierian Press reference books will be included elsewhere in this publication.

Recent research has shown that constrained bistable structures can display negative stiffness behavior and provide extremal vibrational and acoustical absorptive capacity. These bistable structures are therefore compelling candidates for constructing new meta‐materials for noise reduction, anechoic coatings, and backing materials for broadband imaging transducers. To date, demonstrations of these capabilities have been primarily theoretical because the geometry of bistable elements is difficult to construct and refine with conventional manufacturing methods and materials. The purpose of this paper is to leverage the geometric design freedoms provided by selective laser sintering (SLS) technology to design and construct constrained bistable structures with negative stiffness behavior.

A meso‐scale negative stiffness system is designed and fabricated with SLS technology. The system includes a bistable structure in the form of a pre‐compressed/pre‐buckled beam. The dynamic transmissibility of the system is measured, and its behavior is compared to the predictions of analytical models.

Experimental results demonstrate that pre‐compression and pre‐buckling can be used to induce negative stiffness behavior and thereby increase the damping and shift the resonant frequency of an unconstrained beam.

The results support the usefulness of SLS and other additive manufacturing technologies for acoustic and dynamic applications. Specifically, the demonstrated advantages of SLS include the ability to rapidly redesign, functionally 2 prototype, and tune physical models for acoustic and dynamic experimentation. Of significant importance is the ability of SLS to enable consolidation of parts that are traditionally separate, thereby reducing vibrational noise in these systems. In this specific application, SLS enables a proof‐of‐concept comparison of the theoretical and experimental behavior of a meso‐scale negative stiffness system. The demonstrated acoustical and vibrational absorptive capacity of these systems is expected to lead to designs for new structures and materials that offer significantly improved energy absorbing capabilities over a broad range of tunable frequencies without compromising structural stiffness.

Current issues of Publishers' Weekly are reporting serious shortages of paper, binders board, cloth, and other essential book manufacturing materials. Let us assure you these shortages are very real and quite severe.

The purpose of this paper is to review research on lapse in life insurance and to outline potential new areas of research in this field.

The authors consider theoretical lapse rate models as well as empirical research on life insurance lapse and provide a classification of these two streams of research. More than 50 theoretical and empirical papers from this important field of research are reviewed. Challenges for lapse rate modeling, lapse risk mitigation techniques, and possible trends in future lapse behavior are discussed.

Lapse rate modeling has been a very active field of research in the last years, as evidenced by the 44 papers on lapse modeling considered in this review. Moreover, a fair amount of empirical work (another 12 papers) has been done, especially on the issue of how environmental variables affect lapse. Research on individual policyholder and contract information is more scarce, since such information is typically treated as confidential.

The risks arising from lapse are of high economic importance. Lapsation is thus of interest not only to academics, but is highly relevant for the industry, regulators, and policymakers, especially in regard to designing an appropriate regulatory environment. Lapsation also impacts many actuarial tasks, such as product design, pricing, hedging, and risk management. A review of the recent literature might be helpful for these tasks.

To the best of the authors' knowledge, this is the first structured review of the increasingly important literature on life insurance lapsation. Next to the structured review of the existing models and the empirical evidence, the paper also contributes to the literature by discussing challenges for lapse rate modeling and possible trends.

The purpose of this paper is to study the behavior of negative stiffness beams when arranged in a honeycomb configuration and to compare the energy absorption capacity of these negative stiffness honeycombs with regular honeycombs of equivalent relative densities.

A negative stiffness honeycomb is fabricated in nylon 11 using selective laser sintering. Its force-displacement behavior is simulated with finite element analysis and experimentally evaluated under quasi-static displacement loading. Similarly, a hexagonal honeycomb of equivalent relative density is also fabricated and tested. The energy absorbed for both specimens is computed from the resulting force-displacement curves. The beam geometry of the negative stiffness honeycomb is optimized for maximum energy absorption per unit mass of material.

Negative stiffness honeycombs exhibit relatively large positive stiffness, followed by a region of plateau stress as the cell walls buckle, similar to regular hexagonal honeycombs, but unlike regular honeycombs, they demonstrate full recovery after compression. Representative specimens are found to absorb about 65 per cent of the energy incident on them. Optimizing the negative stiffness beam geometry can result in energy-absorbing capacities comparable to regular honeycombs of similar relative densities.

The honeycombs were subject to quasi-static displacement loading. To study shock isolation under impact loads, force-controlled loading is desirable. However, the energy absorption performance of the negative stiffness honeycombs is expected to improve under force-controlled conditions. Additional experimentation is needed to investigate the rate sensitivity of the force-displacement behavior of the negative stiffness honeycombs, and specimens with various geometries should be investigated.

The findings of this study indicate that recoverable energy absorption is possible using negative stiffness honeycombs without sacrificing the high energy-absorbing capacity of regular honeycombs. The honeycombs can find usefulness in a number of unique applications requiring recoverable shock isolation, such as bumpers, helmets and other personal protection devices. A patent application has been filed for the negative stiffness honeycomb design.

This article analyzes two of the determinants of the effectiveness of the mediation process, namely the impact of different mediators and mediation behavior on mediation outcomes in international relations. We review the literature and consider this relationship in terms of specific hypotheses concerning (1) the identity of a mediator, (2) previous interactions with the parties, (3) previous mediation attempts, and (4) the nature of mediation strategy. An original data set of 97 international disputes and 364 mediation attempts in the post‐1945 period is utilized to test our hypotheses. Multivariate analysis suggests the significance of high mediator rank, directive strategy, and close political alignment in achieving successful outcomes. We use these results to posit and test a series of causal models of mediation.

Daring to challenge the status quo impacts innovation. Yet, successful outcomes depend on individual risk-taking and choice to influence others to support new ideas. This Challenging the Status Quo exercise illustrates how leaders use power and influencing tactics to challenge norms by analyzing Donald Trump’s journey as the 45^th U.S. President to defy experts and successfully influence followers to support his non-traditional candidacy: businessman lacking political experience becoming leader of the free world. Through integrating videoclips and polls, instructors make power visible, relevant, and thought-provoking as students apply power theory and influencing tactics perspectives to analyze (a) how leaders impact followers’ perceptions, (b) students mutual-influencing strategies, (c) power’s relationship with social identity and privilege, and (d) social impact on innovation via activism and free speech.

Film provides an alternative medium for assessing our interpretations of cultural icons. This selective list looks at the film and video sources for information on and interpretations of the life of Woody Guthrie.

The purpose of this study is to gain a broad understanding of public perceptions of the police and violence.

This study uses survey data collected from a nationally representative sample (N = 1,223) by the National Opinion Research Center (NORC) Center for Public Affairs Research at the University of Chicago. Descriptive, bivariate correlational and multivariate regression analyses of the data were conducted.

Descriptive analyses show the populace is equally concerned about the police use of violence and violence against the police, but bivariate analyses indicate the two types of concern are unrelated, and multivariate regression analyses show that few variables impact both types of concern. Consistent with prior research, young people and racial/ethnic minorities reported greater concerns about police violence than did older adults and Whites, yet neither age nor race/ethnicity impacted concerns about violence against the police. Perceived mistreatment by the police was the only variable which impacted perceptions of police violence and violence against the police in a consistent and cogent manner.

This study is the first to examine public perceptions of the police as both the agents and victims of violence. The results indicate public perceptions of the police are more complex than was previously believed.