Liquid-vapor interface locations in a spheroidal container under low gravity

As a part of the general study of liquid behavior in low gravity environments, an experimental investigation was conducted to determine if there are equilibrium liquid-vapor interface configurations that can exist at more than one location in oblate spheroidal containers under reduced gravity conditions. Static contact angles of the test liquids on the spheroid surface were restricted to near 0 deg. The experiments were conducted in a low gravity environment. An oblate spheroidal tank was tested with an eccentricity of 0.68 and a semimajor axis of 2.0 cm. Both quantitative and qualitative data were obtained on the liquid-vapor interface configuration and position inside the container. The results of these data, and their impat on previous work in this area, are discussed. Of particular interest are those equilibrium interface configurations that can exist at multiple locations in the container

NASA Lewis Research Center low-gravity fluid management technology program

A history of the Lewis Research Center in space fluid management technology program is presented. Current programs which include numerical modeling of fluid systems, heat exchanger/radiator concept studies, and the design of the Cryogenic Fluid Management Facility are discussed. Recent analytical and experimental activities performed to support the Shuttle/Centaur development activity are highlighted

Diffraction Analysis of 2-D Pupil Mapping for High-Contrast Imaging

Pupil-mapping is a technique whereby a uniformly-illuminated input pupil, such as from starlight, can be mapped into a non-uniformly illuminated exit pupil, such that the image formed from this pupil will have suppressed sidelobes, many orders of magnitude weaker than classical Airy ring intensities. Pupil mapping is therefore a candidate technique for coronagraphic imaging of extrasolar planets around nearby stars. Unlike most other high-contrast imaging techniques, pupil mapping is lossless and preserves the full angular resolution of the collecting telescope. So, it could possibly give the highest signal-to-noise ratio of any proposed single-telescope system for detecting extrasolar planets. Prior analyses based on pupil-to-pupil ray-tracing indicate that a planet fainter than 10^{-10} times its parent star, and as close as about 2 lambda/D, should be detectable. In this paper, we describe the results of careful diffraction analysis of pupil mapping systems. These results reveal a serious unresolved issue. Namely, high-contrast pupil mappings distribute light from very near the edge of the first pupil to a broad area of the second pupil and this dramatically amplifies diffraction-based edge effects resulting in a limiting attainable contrast of about 10^{-5}. We hope that by identifying this problem others will provide a solution.Comment: 23 pages, 13 figures, also posted to http://www.orfe.princeton.edu/~rvdb/tex/piaaFresnel/ms.pd

Classifying the embedded young stellar population in Perseus and Taurus & the LOMASS database

Context. The classification of young stellar objects (YSOs) is typically done using the infrared spectral slope or bolometric temperature, but either can result in contamination of samples. More accurate methods to determine the evolutionary stage of YSOs will improve the reliability of statistics for the embedded YSO population and provide more robust stage lifetimes. Aims. We aim to separate the truly embedded YSOs from more evolved sources. Methods. Maps of HCO+ J=4-3 and C18O J=3-2 were observed with HARP on the James Clerk Maxwell Telescope (JCMT) for a sample of 56 candidate YSOs in Perseus and Taurus in order to characterize emission from high (column) density gas. These are supplemented with archival dust continuum maps observed with SCUBA on the JCMT and Herschel PACS to compare the morphology of the gas and dust in the protostellar envelopes. The spatial concentration of HCO+ J=4-3 and 850 micron dust emission are used to classify the embedded nature of YSOs. Results. Approximately 30% of Class 0+I sources in Perseus and Taurus are not Stage I, but are likely to be more evolved Stage II pre-main sequence (PMS) stars with disks. An additional 16% are confused sources with an uncertain evolutionary stage. Conclusions. Separating classifications by cloud reveals that a high percentage of the Class 0+I sources in the Perseus star forming region are truly embedded Stage I sources (71%), while the Taurus cloud hosts a majority of evolved PMS stars with disks (68%). The concentration factor method is useful to correct misidentified embedded YSOs, yielding higher accuracy for YSO population statistics and Stage timescales. Current estimates (0.54 Myr) may overpredict the Stage I lifetime on the order of 30%, resulting in timescales of 0.38 Myr for the embedded phase.Comment: 33 pages, 21 figures, 6 tables, Accepted to be published in A&

Decimal growth stages for precision wheat production in changing environments?

The utility of the decimal growth stage (DGS) scoring system for cereals is reviewed. The DGS is the most widely used scale in academic and commercial applications because of its comprehensive coverage of cereal developmental stages, the ease of use and definition provided and adoption by official agencies. The DGS has demonstrable and established value in helping to optimise the timing of agronomic inputs, particularly with regard to plant growth regulators, herbicides, fungicides and soluble nitrogen fertilisers. In addition, the DGS is used to help parameterise crop models, and also in understanding the response and adaptation of crops to the environment. The value of the DGS for increasing precision relies on it indicating, to some degree, the various stages in the development of the stem apex and spike. Coincidence of specific growth stage scores with the transition of the apical meristem from a vegetative to a reproductive state, and also with the period of meiosis, is unreliable. Nonetheless, in pot experiments it is shown that the broad period of booting (DGS 41–49) appears adequate for covering the duration when the vulnerability of meiosis to drought and heat stress is exposed. Similarly, the duration of anthesis (61–69) is particularly susceptible to abiotic stresses: initially from a fertility perspective, but increasingly from a mean grain weight perspective as flowering progresses to DGS 69 and then milk development. These associations with DGS can have value at the crop level of organisation: for interpreting environmental effects, and in crop modelling. However, genetic, biochemical and physiological analysis to develop greater understanding of stress acclimation during the vegetative state, and tolerance at meiosis, does require more precision than DGS can provide. Similarly, individual floret analysis is needed to further understand the genetic basis of stress tolerance during anthesis

Increased H2_2CO production in the outer disk around HD 163296

Three formaldehyde lines were observed (H$_2$CO 3$_{03}$--2$_{02}$, H$_2$CO 3$_{22}$--2$_{21}$, and H$_2$CO 3$_{21}$--2$_{20}$) in the protoplanetary disk around the Herbig Ae star HD 163296 with ALMA at 0.5 arcsecond (60 AU) spatial resolution. H$_2$CO 3$_{03}$--2$_{02}$ was readily detected via imaging, while the weaker H$_2$CO 3$_{22}$--2$_{21}$ and H$_2$CO 3$_{21}$--2$_{20}$ lines required matched filter analysis to detect. H$_2$CO is present throughout most of the gaseous disk, extending out to 550 AU. An apparent 50 AU inner radius of the H$_2$CO emission is likely caused by an optically thick dust continuum. The H$_2$CO radial intensity profile shows a peak at 100 AU and a secondary bump at around 300 AU, suggesting increased production in the outer disk. Different parameterizations of the H$_2$CO abundance were compared to the observed visibilities with $\chi^2$ minimization, using either a characteristic temperature, a characteristic radius or a radial power law index to describe the H$_2$CO chemistry. Similar models were applied to ALMA Science Verification data of C$^{18}$O. In all modeling scenarios, fits to the H$_2$CO data show an increased abundance in the outer disk. The overall best-fit H$_2$CO model shows a factor of two enhancement beyond a radius of 270$\pm$20 AU, with an inner abundance of $2\!-\!5 \times 10^{-12}$. The H$_2$CO emitting region has a lower limit on the kinetic temperature of $T > 20$ K. The C$^{18}$O modeling suggests an order of magnitude depletion in the outer disk and an abundance of $4\!-\!12 \times 10^{-8}$ in the inner disk. The increase in H$_2$CO outer disk emission could be a result of hydrogenation of CO ices on dust grains that are then sublimated via thermal desorption or UV photodesorption, or more efficient gas-phase production beyond about 300 AU if CO is photodisocciated in this region

Membrane protein alterations in rodent erythrocytes and synaptosomes due to aging and hyperoxia

AbstractWe have applied the technique of electron paramagnetic resonance (EPR) protein-specific spin labeling to the study of membrane protein alterations occurring during age and exposure to isobaric hyperoxia. Cortical synaptosomes and erythrocyte membranes (ghosts) were isolated from young rodents (Fisher 344 rats or mongolian gerbils, 3–4 months of age) and aged rodents (age 22–27 months for rats, greater than 15 months for gerbils). Membrane proteins were spin labeled with the thiol-specific spin label MAL-6 (2,2,6,6,-tetramethyl-4-maleimido-piperdin-1-oxyl). The relevant EPR spectral parameter of MAL-6 labeled membranes, the W/S ratio, decreased significantly with age of animal in both synaptosomes and ghosts (P < 0.001). As a paradigm for accelerated oxidative stress, young and aged gerbils were exposed to an atmosphere of 90–100% O2 for 0–48 h. In both young and aged gerbils, the W/S ratio decreased significantly with hyperoxic stress (P < 0.003). The W/S ratio of synaptosomes isolated from aged gerbils decreased continually from 0–48 h hyperoxia, whereas the W/S ratio of synaptosomes from young animals demonstrated a pronounced rebound effect from 24–48 h. The results are discussed with reference to membrane protein oxidation in aging

Concretizing God - Fetishism and the Social Construction of Objects

This thesis investigates the agency of objects within the context of contemporary art discourse by viewing them through the lens of fetishism. The fetish has been widely used to describe a material object that possesses some concentrated force or power beyond its materiality - a power that is somehow inordinate, misplaced or inflated (Graeber, 2005: 434). This power is mediated and maintained socially, dependent upon particular beliefs and activated the moment it is interacted with. In this sense, by viewing objects as agential, fetishism constitutes a social theory of objects, and furthermore a condition wherein objects are capable of becoming autonomous social entities in their own right. The research is positioned within the contextual field of socially engaged art practice, with particular emphasis to Relational Aesthetics by Nicolas Bourriaud (Bourriaud, 2002: 112), which was written in relation to the growing prevalence of socially engaged practice as he saw it emerging in the 1990s (Ibid). However, an optical contemplation of objects as an inherently social activity is negated from Bourriaud’s writing (Bishop, 2005: 62). The research has found that fetishism provides a useful means with which to understand both the social and participatory implications of objects within the context of contemporary art. I have investigated these capacities using a practiceled methodology, wherein my art practice has developed alongside my engagement with the literature, which I have used in tandem in order to further my understanding of fetishism and its relationship to contemporary art discourse. I have subsequently produced three sculptures and one public intervention which have been photographically documented, as well as autoethnographic responses of my own mental process of creating them. The research has subsequently identified and explored three crucial topics on the fetishistic capacities of objects within this context; their death, their life and the illusion they create