Alien Registration- Hatt, Cecil M. (Gorham, Cumberland County)

https://digitalmaine.com/alien_docs/31936/thumbnail.jp

Mechanical design aspects of a tri-axial accelerometer

This work describes the development of computer models for the design of a novel three-axis silicon accelerometer with thin-film PZT piezo-electric sensing. Theoretical and finite element methods are used to predict the resonant frequencies, resonant mode shapes, and charge sensitivity of the accelerometers. The strengths of each analytical method are used to allow the identification of trends in geometrical affects, and to optimise the design with respect to specification objectives for a commercial device. The theoretical models have been developed and refined in conjunction with practical fabrication trials. This has allowed the material properties to be derived, specific to the thin-film deposition method used, and incorporated onto the models. The practical fabrication process has raised a number of unforeseen issues, and these have led to changes from the original design. These changes have been analysed with the theoretical models, and revised performance predictions produced. The practical findings are consistent with the revised predictions, and achieve close to the desired performance specification.MPhi

Purinergic receptor antagonists inhibit odorant-mediated CREB phosphorylation in sustentacular cells of mouse olfactory epithelium

<p>Abstract</p> <p>Background</p> <p>Extracellular nucleotides have long been known to play neuromodulatory roles and to be involved in intercellular signalling. In the olfactory system, ATP is released by olfactory neurons, and exogenous ATP can evoke an increase in intracellular calcium concentration in sustentacular cells, the nonneuronal supporting cells of the olfactory epithelium. Here we investigate the hypothesis that olfactory neurons communicate with sustentacular cells via extracellular ATP and purinergic receptor activation.</p> <p>Results</p> <p>Here we show that exposure of mice to a mixture of odorants induced a significant increase in the levels of the transcription factor CREB phosphorylated at Ser-133 in the nuclei of both olfactory sensory neurons and sustentacular cells. This activation was dependent on adenylyl cyclase III-mediated olfactory signaling and on activation of P2Y purinergic receptors on sustentacular cells. Purinergic receptor antagonists inhibited odorant-dependent CREB phosphorylation specifically in the nuclei of the sustentacular cells.</p> <p>Conclusion</p> <p>Our results point to a possible role for extracellular nucleotides in mediating intercellular communication between the neurons and sustentacular cells of the olfactory epithelium in response to odorant exposure. Maintenance of extracellular ionic gradients and metabolism of noxious chemicals by sustentacular cells may therefore be regulated in an odorant-dependent manner by olfactory sensory neurons.</p

A multifractal approach to space-filling recovery for PET quantification.

Purpose: A new image-based methodology is developed for estimating the apparent space-filling properties of an object of interest in PET imaging without need for a robust segmentation step and used to recover accurate estimates of total lesion activity (TLA). Methods: A multifractal approach and the fractal dimension are proposed to recover the apparent space-filling index of a lesion (tumor volume, TV) embedded in nonzero background. A practical implementation is proposed, and the index is subsequently used with mean standardized uptake value (SUVmean) to correct TLA estimates obtained from approximate lesion contours. The methodology is illustrated on fractal and synthetic objects contaminated by partial volume effects (PVEs), validated on realistic 18F-fluorodeoxyglucose PET simulations and tested for its robustness using a clinical 18F-fluorothymidine PET test-retest dataset. Results: TLA estimates were stable for a range of resolutions typical in PET oncology (4-6 mm). By contrast, the space-filling index and intensity estimates were resolution dependent. TLA was generally recovered within 15% of ground truth on postfiltered PET images affected by PVEs. Volumes were recovered within 15% variability in the repeatability study. Results indicated that TLA is a more robust index than other traditional metrics such as SUVmean or TV measurements across imaging protocols. Conclusions: The fractal procedure reported here is proposed as a simple and effective computational alternative to existing methodologies which require the incorporation of image preprocessing steps (i.e., partial volume correction and automatic segmentation) prior to quantification

Temperature Driven Structural Phase Transition in Tetragonal-Like BiFeO3

Highly-strained BiFeO3 exhibits a "tetragonal-like, monoclinic" crystal structure found only in epitaxial films (with an out-of-plane lattice parameter exceeding the in-plane value by >20%). Previous work has shown that this phase is properly described as a M$_{C}$ monoclinic structure at room temperature [with a (010)$_{pc}$ symmetry plane, which contains the ferroelectric polarization]. Here we show detailed temperature-dependent x-ray diffraction data that evidence a structural phase transition at ~100C to a high-temperature M$_{A}$ phase ["tetragonal-like" but with a (1-10)$_{pc}$ symmetry plane]. These results indicate that the ferroelectric properties and domain structures of strained BiFeO$_3$ will be strongly temperature dependent.Comment: 10 pages, 3 figure

The influence of alfalfa-switchgrass intercropping on microbial community structure and function

The use of nitrogen fertilizer on bioenergy crops such as switchgrass results in increased costs, nitrogen leaching and emissions of N2O, a potent greenhouse gas. Intercropping with nitrogen-fixing alfalfa has been proposed as an environmentally sustainable alternative, but the effects of synthetic fertilizer versus intercropping on soil microbial community functionality remain uncharacterized. We analysed 24 metagenomes from the upper soil layer of agricultural fields from Prosser, WA over two growing seasons and representing three agricultural practices: unfertilized switchgrass (control), fertilized switchgrass and switchgrass intercropped with alfalfa. The synthetic fertilization and intercropping did not result in major shifts of microbial community taxonomic and functional composition compared with the control plots, but a few significant changes were noted. Most notably, mycorrhizal fungi, ammonia-oxidizing archaea and bacteria increased in abundance with intercropping and fertilization. However, only betaproteobacterial ammonia-oxidizing bacteria abundance in fertilized plots significantly correlated to N2O emission and companion qPCR data. Collectively, a short period of intercropping elicits minor but significant changes in the soil microbial community toward nitrogen preservation and that intercropping may be a viable alternative to synthetic fertilization

Herbivorous reptiles and body mass: Effects on food intake, digesta retention, digestibility and gut capacity, and a comparison with mammals

Differences in the allometric scaling between gut capacity (with body mass, BM1.00) and food intake (with BM0.75) should theoretically result in a scaling of digesta retention time with BM0.25 and therefore a higher digestive efficiency in larger herbivores. This concept is an important part of the so-called ‘Jarman-Bell principle’ (JBP) that explains niche differentiation along a body size gradient in terms of digestive physiology. Empirical data in herbivorous mammals, however, do not confirm the scaling of retention time, or of digestive efficiency, with body mass. Here, we test these concepts in herbivorous reptiles, adding data of an experiment that measured food intake, digesta retention, digestibility and gut capacity in 23 tortoises (Testudo graeca, T. hermanni , Geochelone nigra, G. sulcata, Dipsochelys dussumieri) across a large BM range (0.5-180 kg) to a literature data collection. While dry matter gut fill scaled to BM1.07 and dry matter intake to BM0.76, digesta mean retention time (MRT) scaled to BM0.17; the scaling exponent was not significantly different from zero for species > 1 kg. Food intake level was a major determinant of MRT across reptiles and mammals. In contrast to dietary fibre level, BM was not a significant contributor to dry matter digestibility in a General Linear Model. Digestibility coefficients in reptiles depended on diet nutrient composition in a similar way as described in mammals. Although food intake is generally lower and digesta retention longer in reptiles than in mammals, digestive functions scale in a similar way in both clades, indicating universal principles in herbivore digestive physiology. The reasons why the theoretically derived JBP has little empirical support remain to be investigated. Until then, the JBP should not be evoked to explain niche differentiation along a body size axis in terms of digestive physiology

Evaluation de méthodes de segmentation bayésiennes pour l'imagerie TEP en oncologie

Ce travail se concentre sur l'étude de méthodes de segmentation statistiques pour la détermination des volumes fonctionnels dans le cadre de l'imagerie TEP avec des applications en oncologie, en particulier la radiothérapie. Nous présentons ici une comparaison des performances de différentes approches (locale et globale, « dure » et « floue ») pour des images réelles d'acquisitions TEP du fantôme IEC. Les résultats obtenus sur images simulées sont ici confirmés: la méthode locale est la mieux adaptée, et fonctionne mieux que l'approche par chaînes de Markov cachées et la méthode de référence par seuillage