3D-Printed Miniature Robots with Piezoelectric Actuation for Locomotion and Steering Maneuverability Applications

The miniaturization of robots with locomotion abilities is a challenge of significant technological impact in many applications where large-scale robots have physical or cost restrictions. Access to hostile environments, improving microfabrication processes, or advanced instrumentation are examples of their potential use. Here, we propose a miniature 20 mm long sub-gram robot with piezoelectric actuation whose direction of motion can be controlled. A differential drive approach was implemented in an H-shaped 3D-printed motor platform featuring two plate resonators linked at their center, with built-in legs. The locomotion was driven by the generation of standing waves on each plate by means of piezoelectric patches excited with burst signals. The control of the motion trajectory of the robot, either translation or rotation, was attained by adjusting the parameters of the actuation signals such as the applied voltage, the number of applied cycles, or the driving frequency. The robot demonstrated locomotion in bidirectional straight paths as long as 65 mm at 2 mm/s speed with a voltage amplitude of only 10 V, and forward and backward precise steps as low as 1 µm. The spinning of the robot could be controlled with turns as low as 0.013 deg. and angular speeds as high as 3 deg./s under the same conditions. The proposed device was able to describe complex trajectories of more than 160 mm, while carrying 70 times its own weight.

Patterns of parent and offspring gene expression reflect canalization, not plasticity, in response to environmental stress

Parenting buffers offspring from hostile environments, but it is not clear how or if the genes that underlie parenting change their expression under environmental stress. We recently demonstrated that for the subsocial carrion beetle, Nicrophorus orbicollis, temperature during parenting does not affect parenting phenotypes. Here, we ask if transcriptional changes associated with parenting are likewise robust to environmental stress. The absence of a transcriptional response for parenting under stress would suggest that the genetic programs for parenting and being parented are canalized. Conversely, a robust transcriptional response would suggest that plasticity of underlying gene expression is critical for maintaining behavioral stability, and that these mechanisms provide a potential target for selection in the face of environmental change. We test these alternatives by characterizing gene expression of parents and offspring with and without parent-offspring interactions under a benign and a stressful temperature. We found that parent-offspring interactions elicit distinct transcriptional responses of parents and larvae irrespective of temperature. We further detected robust changes of gene expression in beetles breeding at 24 degrees C compared to 20 degrees C irrespective of family interaction. However, no strong interaction between parent-offspring interaction and temperature was detected for either parents or larvae. We therefore conclude that canalization, not plasticity of gene expression, most likely explains the absence of behavioral plasticity under thermal stress. This result suggests that species may not have the genetic variation needed to respond to all environmental change, especially for complex phenotypes.

Anticipated Food Scarcity and Food Preferences

In the recent decade, marketing literature has acknowledged the advantages of applying an evolutionary lens to understand consumer behavior in different domains. Food choice context is one such domain, having implications for societal well-being, especially for public health and addressing environmental issues. In this thesis, I investigate how mechanisms that have emerged as adaptations to food scarcity—frequent throughout human history—affect modern consumers’ food preferences, potentially leading to maladaptive outcomes. In Paper I, we highlight that selection pressures adjusted humans to forage in ancestral, hostile environments when they were wandering between periods of food scarcity and food sufficiency. Consequently, consumers often fail to choose foods appropriate to their current needs in contemporary retail contexts. Rather than attempting to override these hardwired and evolutionarily outdated food preferences, we recommend policymakers leverage them in such a way that facilitates healthier food choices. A series of studies reported in Paper II show that exposing people to climate change-induced food scarcity distant in time and space shifts their current food preferences. Specifically, people exposed to such video content exhibit a stronger preference toward energy-dense (vs. low-calorie) foods than their peers exposed to a control video. In Paper III, we aimed to account for potential confounds stemming from the control video used in studies reported in Paper II. Additionally, we strived to conceptually replicate these earlier findings by exposing participants to subtle cues to food scarcity—a winter forest walk. Although not all studies yielded significant results at conventional levels, this empirical package—when taken together—corroborated the earlier findings. Despite that studies described in Papers II–III provided a shred of empirical evidence showing a potency of food scarcity cues in increasing preferences toward energy-dense (vs. low-calorie) products, it was still unclear what drove such a shift in food liking. Thus, in Paper IV, we have developed and psychometrically validated the Anticipated Food Scarcity Scale (AFSS), measuring the degree to which people perceive food resources as becoming less available in the future. Aside from being a candidate mechanism partially explaining findings reported in Papers II–III, anticipated food scarcity (AFS) is also related to some aspects of prosociality. Studies presented in this thesis suggest that when environmental cues to food scarcity are present, people show a stronger preference toward energy-dense (vs. low-calorie) foods than their peers unexposed to such cues. Policymakers should consider these results when designing climate change and other similar campaigns, as such communication often depicts food scarcity. Additional research may explore the possibility that exposure to food scarcity cues affects food choices. Considering that we found AFS correlated with certain prosocial attitudes, it is a new psychological construct that warrants future investigation through multidisciplinary research.

Viewing the American West as a Chicana in China

In both scholarly work and popular imagination, the American West is the final destination of migrant from Europe and Mexico. The stories of those migrants, however, obscure the first migration (12,000 BP) from Asia into North America. That migration across the now-submerged land bridge of Beringia ended humanity’s millennia-long journey across the globe that originated in Africa more than 50,000 years earlier. Using two examples, this essay reflects on how the Asian origins of the first Americans have been transformed into myths that conceal humanity’s migratory nature. First, in Chinese Communist propaganda, those origins are transformed into the myth of Peking Man as a branch of humanity originating in China rather than Africa. Second, in the writing of Rudolfo Anaya, those Asian origins are transformed into the myth of homogenous “Brown Brothers” united against white imperialists. Rather than rely on a myth of racial unity in some original homeland, this essay urges reliance on the shared experience of migration and home-making in hostile environments as the true source of our common humanity. Anaya’s Golden Carp, symbol of the life-giving fierce of water in an arid environment, captures this common human predicament stretching from Tibet and Xinjiang to New Mexico, epitomizing the American West as the place where humanity has been reunited, the home to the last wanderers of the human race.

Neural networks on-line optimized PID controller with wind gust rejection for a quad-rotor

In this paper a complete methodology of modeling and control of quad-rotor aircraft is exposed. In fact, a PD on-line optimized Neural Networks Approach (PD-NN) is developed and applied to control the attitude of a quad-rotor that is evolving in hostile environment with wind gust disturbances and should maintain its position despite of these troubles. Whereas PD classical controllers are dedicated for the positions, altitude and speed control. The main objective of this work is to develop a smart Self-Tuning PD controller for attitude angles control, based on neural networks capable of controlling the quad-rotor for an optimized performance thus following a desired trajectory. Many problems could arise if the quad-rotor is evolving in hostile environments presenting irregular troubles such as wind gusts modeled and applied to the overall system. The quad-rotor has to rapidly achieve tasks while guaranteeing stability and precision and must behave quickly with regards to decision making fronting turbulences. This technique offers some advantages over conventional control methods such as PD controllers. Simulation results are achieved with the use of Matlab/Simulink environment and are established on a comparative study between PD and PD-NN controllers founded on wind disturbances application. These obstacles are applied with numerous degrees of strength to test the quad-rotor comportment. Experimental results are reached with the use of the V-REP environment with which some trajectories are tracked and then applied on a BLADE Inductrix FPV+. These simulations and experimental results are acceptable and have confirmed the efficiency of the proposed PD-NN approach. In fact, this controller has fairly smaller errors than the PD controller and has an improved ability to reject troubles. Moreover, it has confirmed to be extremely vigorous and efficient fronting disturbances in the form of wind disturbances.

Anticipated Food Scarcity and Food Preferences: Ph.D. thesis

In the recent decade, marketing literature has acknowledged the advantages of applying an evolutionary lens to understand consumer behavior in different domains. Food choice context is one such domain, having implications for societal well-being, especially for public health and addressing environmental issues. In this thesis, I investigate how mechanisms that have emerged as adaptations to food scarcity—frequent throughout human history—affect modern consumers’ food preferences, potentially leading to maladaptive outcomes. In Paper I, we highlight that selection pressures adjusted humans to forage in ancestral, hostile environments when they were wandering between periods of food scarcity and food sufficiency. Consequently, consumers often fail to choose foods appropriate to their current needs in contemporary retail contexts. Rather than attempting to override these hardwired and evolutionarily outdated food preferences, we recommend policymakers leverage them in such a way that facilitates healthier food choices. A series of studies reported in Paper II show that exposing people to climate changeinduced food scarcity distant in time and space shifts their current food preferences. Specifically, people exposed to such video content exhibit a stronger preference toward energy-dense (vs. low-calorie) foods than their peers exposed to a control video. In Paper III, we aimed to account for potential confounds stemming from the control video used in studies reported in Paper II. Additionally, we strived to conceptually replicate these earlier findings by exposing participants to subtle cues to food scarcity—a winter forest walk. Although not all studies yielded significant results at conventional levels, this empirical package—when taken together—corroborated the earlier findings. Despite that studies described in Papers II–III provided a shred of empirical evidence showing a potency of food scarcity cues in increasing preferences toward energy-dense (vs. low-calorie) products, it was still unclear what drove such a shift in food liking. Thus, in Paper IV, we have developed and psychometrically validated the Anticipated Food Scarcity Scale (AFSS), measuring the degree to which people perceive food resources as becoming less available in the future. Aside from being a candidate mechanism partially explaining findings reported in Papers II–III, anticipated food scarcity (AFS) is also related to some aspects of prosociality. Studies presented in this thesis suggest that when environmental cues to food scarcity are present, people show a stronger preference toward energy-dense (vs. low-calorie) foods than their peers unexposed to such cues. Policymakers should consider these results when designing climate change and other similar campaigns, as such communication often depicts food scarcity. Additional research may explore the possibility that exposure to food scarcity cues affects food choices. Considering that we found AFS correlated with certain prosocial attitudes, it is a new psychological construct that warrants future investigation through multidisciplinary research.

Novel colistin-EDTA combination for successful eradication of colistin-resistant Klebsiella pneumoniae catheter-related biofilm infections

Development of an effective therapy to overcome colistin resistance in Klebsiella pneumoniae, a common pathogen causing catheter-related biofilm infections in vascular catheters, has become a serious therapeutic challenge that must be addressed urgently. Although colistin and EDTA have successful roles for eradicating biofilms, no in vitro and in vivo studies have investigated their efficacy in catheter-related biofilm infections of colistin-resistant K. pneumoniae. In this study, colistin resistance was significantly reversed in both planktonic and mature biofilms of colistin-resistant K. pneumoniae by a combination of colistin (0.25–1 µg/ml) with EDTA (12 mg/ml). This novel colistin-EDTA combination was also demonstrated to have potent efficacy in eradicating colistin-resistant K. pneumoniae catheter-related biofilm infections, and eliminating the risk of recurrence in vivo. Furthermore, this study revealed significant therapeutic efficacy of colistin-EDTA combination in reducing bacterial load in internal organs, lowering serum creatinine, and protecting treated mice from mortality. Altered in vivo expression of different virulence genes indicate bacterial adaptive responses to survive in hostile environments under different treatments. According to these data discovered in this study, a novel colistin-EDTA combination provides favorable efficacy and safety for successful eradication of colistin-resistant K. pneumonia catheter-related biofilm infections.

Adversarial Modeling in WSN and its Application in Key Distribution

Wireless sensor network (WSN) is the interconnection of very small sensors placed in hostile environments. It results in physically node capturing of a node. These further decreases the performance of key management scheme as number of captured nodes increases. In the paper, we approach the issue of node capturing from adversary view. Adversary is considered more intelligent and aims to capture less nodes with maximum destructiveness in the network. This reduces energy capturing cost of adversary in launching this attack. The proposed models exploit different vulnerable points in the networks to build a matrix based attack model. These use dominating set of nodes with node path vulnerability value to quantify the probability of network compromise. These also focus on low capturing cost nodes with high destructiveness in the network. Later, it also considers the travelling capturing cost which also be minimized. Thus all factors are used to compute final attack matrix. It is shown that above models have improved performance in damaging the network in terms of energy capturing cost and number of attacking rounds.