4,251 research outputs found

    Advanced single permanent magnet axipolar ironless stator ac motor for electric passenger vehicles

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    A program was conducted to design and develop an advanced-concept motor specifically created for propulsion of electric vehicles with increased range, reduced energy consumption, and reduced life-cycle costs in comparison with conventional systems. The motor developed is a brushless, dc, rare-earth cobalt, permanent magnet, axial air gap inductor machine that uses an ironless stator. Air cooling is inherent provided by the centrifugal-fan action of the rotor poles. An extensive design phase was conducted, which included analysis of the system performance versus the SAE J227a(D) driving cycle. A proof-of-principle model was developed and tested, and a functional model was developed and tested. Full generator-level testing was conducted on the functional model, recording electromagnetic, thermal, aerodynamic, and acoustic noise data. The machine demonstrated 20.3 kW output at 1466 rad/s and 160 dc. The novel ironless stator demonstated the capability to continuously operate at peak current. The projected system performance based on the use of a transistor inverter is 23.6 kW output power at 1466 rad/s and 83.3 percent efficiency. Design areas of concern regarding electric vehicle applications include the inherently high windage loss and rotor inertia

    Probing the mechanism of electron capture and electron transfer dissociation using tags with variable electron affinity

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    Electron capture dissociation (ECD) and electron transfer dissociation (ETD) of doubly protonated electron affinity (EA)-tuned peptides were studied to further illuminate the mechanism of these processes. The model peptide FQpSEEQQQTEDELQDK, containing a phosphoserine residue, was converted to EA-tuned peptides via β-elimination and Michael addition of various thiol compounds. These include propanyl, benzyl, 4-cyanobenzyl, perfluorobenzyl, 3,5-dicyanobenzyl, 3-nitrobenzyl, and 3,5-dinitrobenzyl structural moieties, having a range of EA from −1.15 to +1.65 eV, excluding the propanyl group. Typical ECD or ETD backbone fragmentations are completely inhibited in peptides with substituent tags having EA over 1.00 eV, which are referred to as electron predators in this work. Nearly identical rates of electron capture by the dications substituted by the benzyl (EA = −1.15 eV) and 3-nitrobenzyl (EA = 1.00 eV) moieties are observed, which indicates the similarity of electron capture cross sections for the two derivatized peptides. This observation leads to the inference that electron capture kinetics are governed by the long-range electron−dication interaction and are not affected by side chain derivatives with positive EA. Once an electron is captured to high-n Rydberg states, however, through-space or through-bond electron transfer to the EA-tuning tags or low-n Rydberg states via potential curve crossing occurs in competition with transfer to the amide π* orbital. The energetics of these processes are evaluated using time-dependent density functional theory with a series of reduced model systems. The intramolecular electron transfer process is modulated by structure-dependent hydrogen bonds and is heavily affected by the presence and type of electron-withdrawing groups in the EA-tuning tag. The anion radicals formed by electron predators have high proton affinities (approximately 1400 kJ/mol for the 3-nitrobenzyl anion radical) in comparison to other basic sites in the model peptide dication, facilitating exothermic proton transfer from one of the two sites of protonation. This interrupts the normal sequence of events in ECD or ETD, leading to backbone fragmentation by forming a stable radical intermediate. The implications which these results have for previously proposed ECD and ETD mechanisms are discussed

    Coherent Error Suppression in Multi-Qubit Entangling Gates

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    We demonstrate a simple pulse shaping technique designed to improve the fidelity of spin-dependent force operations commonly used to implement entangling gates in trapped-ion systems. This extension of the M{\o}lmer-S{\o}rensen gate can theoretically suppress the effects of certain frequency and timing errors to any desired order and is demonstrated through Walsh modulation of a two-qubit entangling gate on trapped atomic ions. The technique is applicable to any system of qubits coupled through collective harmonic oscillator modes

    ACCESS OF COMPOUNDS TO THE VOMERONASAL ORGAN IN PINE AND MEADOW VOLES

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    Neuroendocrine responses play a critical role in reproduction in every mammalian species, including voles (Richmond S. Stehn, 1976). Disruption of these normal responses can result in: (1) abnormal sexual maturation; (2) abnormal or absent female cycles; (3) pseudopregnancy; (4) blocked pregnancies; or (5) the total absence of courtship and mating. Each of these factors in turn plays a considerable role in population dynamics, especially population density. Therefore, mechanisms which disrupt normal neuroendocrine function could affect population dynamics and reduce population density by affecting changes in one or many of these reproductive processes

    Immunization Alters Body Odor

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    Infections have been shown to alter body odor. Because immune activation accompanies both infection and immunization, we tested the hypothesis that classical immunization might similarly result in the alteration of body odors detectable by trained biosensor mice. Using a Y-maze, we trained biosensor mice to distinguish between urine odors from rabies-vaccinated (RV) and unvaccinated control mice. RV-trained mice generalized this training to mice immunized with the equine West Nile virus (WNV) vaccine compared with urine of corresponding controls. These results suggest that there are similarities between body odors of mice immunized with these two vaccines. This conclusion was reinforced when mice could not be trained to directly discriminate between urine odors of RV- versus WNV-treated mice. Next,we trained biosensor mice to discriminate the urine odors of mice treated with lipopolysaccharide (LPS; a general elicitor of innate immunological responses) from the urine of control mice. These LPS-trained biosensors could distinguish between the odors of LPS-treated mouse urine and RV-treated mouse urine. Finally, biosensor mice trained to distinguish between the odors of RV-treated mouse urine and control mouse urine did not generalize this training to discriminate between the odors of LPS-treated mouse urine and control mouse urine. From these experiments, we conclude that: (1) immunization alters urine odor in similar ways for RV andWNV immunizations; and (2) immune activation with LPS also alters urine odor but in ways different from those of RV and WNV

    Cytokine contributions to alterations of the volatile metabolome induced by inflammation

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    Several studies demonstrate that inflammation affects body odor. Volatile signals associated with inflammation induced by pyrogens like LPS are detectable both by conspecifics and chemical analyses. However, little is known about the mechanisms which translate detection of a foreign molecule or pathogen into a unique body odor, or even how unique that odor may be. Here, we utilized C57BL/6J trained mice to identify the odor of LPS-treated conspecifics to investigate potential pathways between LPS-induced inflammation and changes in body odor, as represented by changes in urine odor. We hypothesized that the change in volatile metabolites could be caused directly by the pro-inflammatory cytokine response mediated by TNF or IL-1b, or by the compensatory anti-inflammatory response mediated by IL-10. We found that trained biosensors generalized learned LPS-associated odors to TNF-induced odors, but not to IL-1b or IL-10-induced odors. Analyses of urine volatiles using headspace gas chromatography revealed distinct profiles of volatile compounds for each treatment. Instrumental discrimination relied on a mixture of compounds, including 2-sec-butyl-4,5-dihydrothiazole, cedrol, nonanal, benzaldehyde, acetic acid, 2- ethyl-1-hexanol, and dehydro-exo-brevicomin. Although interpretation of LDA modeling differed from behavioral testing, it does suggest that treatment with TNF, IL-1b, and LPS can be distinguished by their resultant volatile profiles. These findings indicate there is information found in body odors on the presence of specific cytokines. This result is encouraging for the future of disease diagnosis via analysis of volatiles

    Variability of Pennsylvanian-Permian Carbonate Associations and Implications for NW Pangea Palaeogeography, East-Central British Columbia, Canada

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    Different stages of Pennsylvanian-Permian carbonate sedimentation in east-central British Columbia record a complex history of changing environments influenced by evolving palaeogeography and climate. Newly recognized tectonically controlled features affected the distribution and variability of carbonate associations, providing new interpretations for this portion of the west coast of Pangea. Both a heterozoan (cool water) and photozoan (warm-water) association were identified on either side of a palaeogeographic high here informally termed “Tipinahokan Peninsula”. Cool water carbonates were located outboard, or to the west of this high, an area influenced by upwelling waters. Inboard of this high, a warm, protected sea developed, here termed “Kisosowin Sea”. This configuration and palaeolatitude is similar to that of Baja California, Mexico and the Sea of Cortéz, providing a good modern analog for these deposits where warm water carbonates grow at latitudes otherwise dominated by cool water deposits. The warm sea provided a place for a photozoan association to develop during the Permian when the low latitude NW coast of Pangea was dominated by cool water carbonates

    Differing Alterations of Odor Volatiles among Pathogenic Stimuli

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    Alterations of the volatile metabolome (the collection of volatiles present in secretions and other emanations) that occur in response to inflammation can be detected by conspecifics and chemometric analyses. Using a model system where mouse urinary metabolites are altered by treatment with lipopolysaccharide (found in the outer cell membrane of gram-negative bacteria), we hypothesized that alteration of body odor volatiles will vary according to the pathogen responsible for inducing the inflammation. We tested this hypothesis by treating mice with different immunogens that engage different immune signaling pathways. Results suggest that alterations of body odor volatiles resulting from inflammation do contain detailed information about the type of pathogen that instigated the inflammation and these differences are not merely dependent on the severity of the inflammatory event. These results are encouraging for the future of differential medical diagnosis of febrile diseases by analysis of the volatile metabolome. In particular, our data support the possibility that bacterial infections can be differentiated from viral infections such that antibiotic drug stewardship could be drastically improved by reducing unneeded treatments with antibiotics

    Theoretical study of kinks on screw dislocation in silicon

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    Theoretical calculations of the structure, formation and migration of kinks on a non-dissociated screw dislocation in silicon have been carried out using density functional theory calculations as well as calculations based on interatomic potential functions. The results show that the structure of a single kink is characterized by a narrow core and highly stretched bonds between some of the atoms. The formation energy of a single kink ranges from 0.9 to 1.36 eV, and is of the same order as that for kinks on partial dislocations. However, the kinks migrate almost freely along the line of an undissociated dislocation unlike what is found for partial dislocations. The effect of stress has also been investigated in order to compare with previous silicon deformation experiments which have been carried out at low temperature and high stress. The energy barrier associated with the formation of a stable kink pair becomes as low as 0.65 eV for an applied stress on the order of 1 GPa, indicating that displacements of screw dislocations likely occur via thermally activated formation of kink pairs at room temperature
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