4,848 research outputs found
Development and Characterization of a High Speed Mid-IR Tunable Diode Laser Absorption Spectrometer for CO and CO\u3csub\u3e2\u3c/sub\u3e Detection in Detonation Events
A tunable diode laser absorption spectroscopy system, capable of collecting data at a 10 kHz repetition rate near 4.5 microns. This system was made feasible in recent years due to the development of quantum cascade lasers active in the 4.5 microns region of the spectrum. Reaching into the mid-IR region of the electromagnetic spectrum allowed for an analysis of the fundamental absorption bands for both CO and CO2. The spectral absorption was measured for ethylene, methane, ethane, and propane across a variety of equivalence ratios, at various heights above a Hencken Burner surface. For each fuel, the concentration of CO2 was found to agree with chemical equilibrium analysis (CEA) calculations within approximately 8%. The concentration for CO agreed with CEA but with larger error bounds at approximately 20%. It is believed that such large error can be attributed to taking measurements on a hot band, as well as large amounts of H2O and CO2 absorption in the area. This ultimately resulted the measurement of combustion efficiency, which agreed with expected results with approximately 10% error bounds. With this system\u27s proof of concept, it will be possible to analyze real combustors as well as detonation events
Thanks, but no thanks: women's avoidance of help-seeking in the context of a dependency-related stereotype
The stereotype that women are dependent on men is a commonly verbalized, potentially damaging aspect of benevolent sexism. We investigated how women may use behavioral disconfirmation of the personal applicability of the stereotype to negotiate such sexism. In an experiment (N = 86), we manipulated female college studentsâ awareness that women may be stereotyped by men as dependent. We then placed participants in a situation where they needed help. Women made aware of the dependency stereotype (compared to controls who were not) were less willing to seek help. They also displayed a stronger negative correlation between help-seeking and post help-seeking affect - such that the more help they sought, the worse they felt. We discuss the relevance of these findings for research concerning womenâs help-seeking and their management of sexist stereotyping in everyday interaction. We also consider the implications of our results for those working in domains such as healthcare, teaching and counseling, where interaction with individuals in need and requiring help is common
The asymmetrical anthropocene: resilience and the limits of posthumanism
In this article we critique resilienceâs oft-celebrated overcoming of modern liberal frameworks. We bring work on resilience in geography and cognate fields into conversation with explorations of the âasymmetrical Anthropoceneâ, an emerging body of thought which emphasizes human-nonhuman relational asymmetry. Despite their resonances, there has been little engagement between these two responses to the human/world binary. This is important for changing the terms of the policy debate: engaging resilience through the asymmetrical Anthropocene framing shines a different light upon policy discourses of adaptative management, locating resilience as a continuation of modernityâs anthropocentric will-to-govern. From this vantage point, resilience is problematic, neglecting the powers of nonhuman worlds that are not accessible or appropriable for governmental use. However, this is not necessarily grounds for pessimism. To conclude, we argue that human political agency is even more vital in an indeterminate world
Mutations within the Primer Binding Site of the Human Immunodeficiency Virus Type 1 Define Sequence Requirements Essential for Reverse Transcription
AbstractThe primer binding site (PBS) is involved in two stages during the reverse transcription of the retroviral RNA genome. In the early stage, the PBS provides complementary sequences through which tRNALys,3binds the viral RNA genome to initiate minus-strand DNA synthesis; in the later stages, complementarity between the plus- and minus-strand copies of the PBS is required to facilitate the second template transfer needed to complete reverse transcription. We previously constructed a mutant HIV-1 proviral genome, designated as pHXB2PBS(pheC + 5) (now referred to as pheC + 5), which was used to identify regions of the PBS involved in the initiation and second template transfer steps of reverse transcription. To further define the sequence requirements of the PBS for the initiation of reverse transcription, we have made single nucleotide substitutions within the first six nucleotides of the pheC + 5 PBS. Our results demonstrate that mutations within the first five nucleotides of the PBS which disrupt base paring with tRNALys,3-PBS results in an noninfectious virus; a G-U base pair at position six of the tRNALys,3-PBS complex was tolerated. In contrast to the requirements for initiation, we found that complementary binding between only three base pairs of the plus- and minus-strand PBSs was required for the extension of plus-strand DNA during the second template transfer. Furthermore, regions of the minus-strand DNA of up to 24 nucleotides could be looped-out to facilitate the complementarity required for the completion of plus-strand DNA synthesis. Taken together, the results of our studies demonstrate that different features of the PBS with respect to RNA:RNA and DNA:DNA interactions are required for initiation of reverse transcription and the completion of plus-strand DNA synthesis, respectively
RELATIONSHIP OF GERMINAL CENTERS IN LYMPHOID TISSUE TO IMMUNOLOGICAL MEMORY : I. EVIDENCE FOR THE FORMATION OF SMALL LYMPHOCYTES UPON TRANSFER OF PRIMED SPLENIC WHITE PULP TO SYNGENEIC MICE
The fate, proliferation, and developmental potentialities of cell suspensions made from white pulp containing large germinal centers have been studied in the mouse by transfer of cells labeled with thymidine-3H to lethally irradiated, syngeneic recipients. Radioautographic analyses were made using both smears and sections of a variety of tissues. Thymidine-3H-labeling patterns of white pulp showed that, initially, labeling occurred in a majority of blast and "intermediate cells" but in very few or no small lymphocytes. After intravenous transfer, most of the labeled cells localized in the lymphoid tissues of spleen, lymph nodes, and Peyer's patches. Few cells migrated to the thymus, lung, liver, and intestinal mucosa. Both after intravenous and after intraperitoneal transfer there was a rapid increase in the incidence of labeled small lymphocytes and a decrease of labeled blasts and intermediate cells. This was accompanied by an increase in the grain count of the small lymphocytes and a progressive decrease in the grain counts of the blast cells. Exposure of nonlabeled donor cells to thymidine-3H at various time intervals after transfer indicated that dividing cells were present early after transfer but that their incidence progressively decreased. Between 24 and 48 hr, very little cell division was detectable
Primary and secondary controls on reservoir quality: relationships between lithofacies and the development of deformation bands
Primary sedimentological processes in mixed eolian-fluvial systems can result in lithological variability at the sub-seismic scale. This variation in genetic origin has a direct control on the porosity and permeability of a body of sediment, with variations in lithofacies types, their assemblages and contacts responsible for creating fluid pathways or baffles. Post-depositional near-surface and deep process diagenesis affects original porosity and permeabilities through mineral dissolution and re-precipitation, and the generation of stress induced fractures. Examination of bedrock exposure and drillcore from the depositionally heterogeneous Triassic Sherwood Sandstone of north-west England demonstrates that there is a strong facies control on the presence and type of secondary processes, namely in the form of deformation bands. This is despite the entire range of lithofacies being subject to the same regional and local stresses. The mixed eolian-fluvial Sherwood Sandstone Group exhibits a wide range of facies types which allows a good insight in to those most susceptible to deformation band formation. Preliminary work indicates that the eolian grainfall and grainflow facies types are at most risk of being host to deformation bands above all other facies types (both eolian and fluvial). This is significant as both of these facies have very good permeabilities in excess of 6000 mD (millidarcy), whilst the deformation bands have significantly less ranging from 0.1-10 mD. The deformation bands are also identified to occur in a range of styles that vary from: i) isolated thin (1-2 mm thick) individual seams, ii) complex conjugate interlocking sets, and iii) chaotic thick amalgamations of multiple deformation bands ranging from 5-120 cm thick. Each of the deformation types has been constrained in three dimensions and a range of idealised conceptual models are presented that indicate the potential of effects on reservoir quality
The responses of Tribolium castaneum to wheat germ oil and fungal produced volatiles: Presentation
The red flour beetle Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is a significant pest affecting a wide variety of different stored products around the Globe. Despite its economic impact, there is evidence that the lures currently used in traps to monitor for this species are largely ineffective. Based on the evolutionary history of T. castaneum, and the ecological niche it occupies, the volatiles of wheat germ oil and volatiles produced by grain-associated fungi have the potential to act as attractants for this species. We used electroantennography (EAG) to measure the electrophysiological response elicited by sixty-eight volatile compounds found in wheat germ oil and/or grain-associated fungi in two T. castaneum strains; an established lab population (CTC12 strain) and a recently caught wild population. Many volatile compounds from both sources elicited strong antennal depolarisations, and the responses of both strains were highly correlated. We then tested whether the compounds that triggered the strongest antennal depolarisations also elicited behavioural responses by using Y-tube olfactometer bioassays and identified several compounds attractive to both strains. The discovery of novel compounds that elicit strong EAG signals and behavioural responses could prove useful in the design of improved lures for T. castaneum and other stored product pests. Our future research will identify how effective these attractive volatiles might be when used in combination, and when used under conditions that more closely replicate a stored product environment.The red flour beetle Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is a significant pest affecting a wide variety of different stored products around the Globe. Despite its economic impact, there is evidence that the lures currently used in traps to monitor for this species are largely ineffective. Based on the evolutionary history of T. castaneum, and the ecological niche it occupies, the volatiles of wheat germ oil and volatiles produced by grain-associated fungi have the potential to act as attractants for this species. We used electroantennography (EAG) to measure the electrophysiological response elicited by sixty-eight volatile compounds found in wheat germ oil and/or grain-associated fungi in two T. castaneum strains; an established lab population (CTC12 strain) and a recently caught wild population. Many volatile compounds from both sources elicited strong antennal depolarisations, and the responses of both strains were highly correlated. We then tested whether the compounds that triggered the strongest antennal depolarisations also elicited behavioural responses by using Y-tube olfactometer bioassays and identified several compounds attractive to both strains. The discovery of novel compounds that elicit strong EAG signals and behavioural responses could prove useful in the design of improved lures for T. castaneum and other stored product pests. Our future research will identify how effective these attractive volatiles might be when used in combination, and when used under conditions that more closely replicate a stored product environment
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