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Microelectromechanical Systems (MEMS) energy harvesters have been extensively investigated over the past decade, but increasing power density and long-term reliability under high acceleration and low frequency are still major concerns. This study focused on the development of a low-frequency lead zirconate titanate (PZT) based energy harvester capable of operating at high acceleration >4 g with high power density performance. This study investigates the performance effects of altering the electrode configuration and poling configuration to maximize power density. The study investigated using four different types of electrode configuration consisting of long and short interdigitated electrodes (IDE) to operate in d 33 mode, and traditional parallel plate configuration to operate in d 31 mode. The results were numerically and experimentally validated. The results illustrate that the d 33 mode configuration was able to generate >3200 μW mm -3 with good reliability of up to 4 g. 

Viruses that infect phytoplankton are abundant in all regions of the global ocean. Despite their ubiquity, little is understood regarding how biotic interactions can alter virus infection success as well as the fate of phytoplankton hosts. In previous work, the bacterially derived compound 2-heptyl-4-quinolone (HHQ) has been shown to protect the cosmopolitan coccolithophoreEmiliania huxleyifrom virus-induced mortality. The present study explores the potential mechanisms through which protection is conferred. Using a suite of transmission electron microscopy and physiological diagnostic staining techniques, we show that whenE. huxleyiis exposed to HHQ, viruses can gain entry into cells but viral replication and release is inhibited. These findings are supported by a smaller burst size, as well as lower infectious and total virus production when the host is treated with nanomolar concentrations of HHQ. Additionally, diagnostic staining results indicate that programmed cell death markers commonly associated with viral infection are not activated when infectedE. huxleyiare exposed to HHQ. Together, these results suggest that the ability of HHQ to inhibit infectious viral production protects the alga not from getting infected, but from cell lysis. This work identifies a new mechanistic role of bacterial quorum sensing molecules in mediating viral infections in marine microbial systems.

 

Trabecular bone is a spongy bone tissue that serves as a scaffolding-like support inside many skeletal elements. Previous research found allometric variation in some aspects of trabecular bone architecture (TBA) and bone microstructure, whereas others scale isometrically. However, most of these studies examined very wide size and phylogenetic ranges or focused exclusively on primates or lab mice. We examined the impact of body size on TBA across a smaller size range in the mammalian clade Xenarthra (sloths, armadillos, and anteaters). We µCT-scanned the last six presacral vertebrae of 23 xenarthran specimens (body mass 120 g–35 kg). We collected ten gross-morphology measurements and seven TBA metrics and analyzed them using phylogenetic and nonphylogenetic methods. Most metrics had similar allometries to previous work. However, because ecology and phylogeny align closely in Xenarthra, the phylogenetic methods likely removed some covariance due to ecology; clarifying the impact of ecology on TBA in xenarthrans requires further work. Regressions for Folivora had high P-values and low R-squared values, indicating that the extant sloth sample either is too limited to determine patterns or that the unique way sloths load their vertebral columns causes unusually high TBA variation. The southern three-banded armadillo sits far below the regression lines, which may be related to its ability to roll into a ball. Body size, phylogeny, and ecology impact xenarthran TBA, but parsing these effects is highly complex.

 

The association between student motivation and learning, and changes in motivation across a course, were evaluated for students enrolled in one-semester foundation-level inorganic chemistry courses at multiple postsecondary institutions across the United States. The Academic Motivation Scale for Chemistry (AMS-Chemistry) and the Foundations of Inorganic Chemistry American Chemical Society Exam (i.e., a content knowledge measure) were used in this study. Evidence of validity, reliability, and longitudinal measurement invariance for data obtained from the AMS-Chemistry instrument with this population were found using methodologies appropriate for ordinal, non-parametric data. Positive and significant associations between intrinsic motivation measures and academic performance corroborate theoretical and empirical investigations; however, a lack of pre/post changes in motivation suggest that motivation may be less malleable in courses primarily populated by chemistry majors. Implications for inorganic chemistry instructors include paths for incorporating engaging pedagogies known to promote intrinsic motivation and methods for incorporating affect measures into assessment practices. Implications for researchers include a need for more work that disaggregates chemistry majors when evaluating relationships between affect and learning, and when making pre/post comparisons. Additionally, this work provides an example of how to implement more appropriate methods for treating data in studies using Likert-type responses and nested data. 

The effects of total ionizing dose (TID) on SRAM physical unclonable functions (PUF) are studied through x-ray and proton irradiation of commercially available SRAM. Negative shifts in the Fractional Hamming Weight (FHW) were measured with increasing TID, indicating a migration of bistable cells towards logic low. Additionally, positive shifts in the intra-die Fractional Hamming Distance (FHD) were measured and indicate changes to the virtual fingerprint of an SRAM PUF with TID, especially in devices that were dosed while holding data. Shifts in inter-die FHD were negligible, allowing individual SRAMs still to be easily identified based on the FHD between a known and unknown sample even after moderate amounts of TID. In some cases, SRAMs could still be identified by their PUFs after the devices had failed. In all cases, the irradiated SRAM devices retain their virtual fingerprint after recovery through annealing. 

Chlorophyll (Chl) is widely taken as a proxy for phytoplankton biomass, despite well-known variations in Chl:C:biomass ratios as an acclimative response to changing environmental conditions. For the sake of simplicity and computational efficiency, many large scale biogeochemical models ignore this flexibility, compromising their ability to capture phytoplankton dynamics. Here we evaluate modelling approaches of differing complexity for phytoplankton growth response: fixed stoichiometry, fixed stoichiometry with photoacclimation, classical variable-composition with photoacclimation, and Instantaneous Acclimation with optimal resource allocation. Model performance is evaluated against biogeochemical observations from time-series sites BATS and ALOHA, where phytoplankton composition varies substantially. We analyse the sensitivity of each model variant to the affinity parameters for light and nutrient, respectively. Models with fixed stoichiometry are more sensitive to parameter perturbations, but the inclusion of photoacclimation in the fixed-stoichiometry model generally captures Chl observations better than other variants when individually tuned for each site and when using similar parameter sets for both sites. Compared to the fixed stoichiometry model including photoacclimation, models with variable C:N ratio perform better in cross-validation experiments using model-specific parameter sets tuned for the other site; i.e., they are more portable. Compared to typical variable composition approaches, instantaneous acclimation, which requires fewer state variables, generally yields better performance but somewhat lower portability than the fully dynamic variant. Further assessments using objective optimisation and more contrasting stations are suggested. 

Abstract The elliptic algebras in the title are connected graded $\mathbb {C}$ -algebras, denoted $Q_{n,k}(E,\tau )$ , depending on a pair of relatively prime integers $n>k\ge 1$ , an elliptic curve E and a point $\tau \in E$ . This paper examines a canonical homomorphism from $Q_{n,k}(E,\tau )$ to the twisted homogeneous coordinate ring $B(X_{n/k},\sigma ',\mathcal {L}^{\prime }_{n/k})$ on the characteristic variety $X_{n/k}$ for $Q_{n,k}(E,\tau )$ . When $X_{n/k}$ is isomorphic to $E^g$ or the symmetric power $S^gE$ , we show that the homomorphism $Q_{n,k}(E,\tau ) \to B(X_{n/k},\sigma ',\mathcal {L}^{\prime }_{n/k})$ is surjective, the relations for $B(X_{n/k},\sigma ',\mathcal {L}^{\prime }_{n/k})$ are generated in degrees $\le 3$ and the noncommutative scheme $\mathrm {Proj}_{nc}(Q_{n,k}(E,\tau ))$ has a closed subvariety that is isomorphic to $E^g$ or $S^gE$ , respectively. When $X_{n/k}=E^g$ and $\tau =0$ , the results about $B(X_{n/k},\sigma ',\mathcal {L}^{\prime }_{n/k})$ show that the morphism $\Phi _{|\mathcal {L}_{n/k}|}:E^g \to \mathbb {P}^{n-1}$ embeds $E^g$ as a projectively normal subvariety that is a scheme-theoretic intersection of quadric and cubic hypersurfaces.