1,386 research outputs found
Doppler Tomography of Dwarf Nova IY UMa during Quiescence
Quiescent Doppler tomography of the newly discovered deeply-eclipsing SU UMa
system IY UMa reveals properties of the region where the accretion stream from
the donor impacts the edge of the disc. A very strong bright spot is produced
and the Keplerian disc emission in the impact region is disrupted or obscured.
The differing properties of Halpha, Hbeta and He I emission will allow physical
parameters of the converging flow region to be studied.Comment: 6 pages, 5 figures. To appear in Proceedings of Astro-Tomography
Workshop, Brussels, July 2000, Eds. H. Boffin, D. Steeghs, Springer-Verlag
Lecture Notes in Physic
The detection of the donor star in IY UMa
We present the results of a search for the donor star in the high inclination
SU UMa type cataclysmic variable IY UMa. We detect absorption features in the
near infrared consistent with an M type dwarf donor star. Using the skew
mapping technique to exploit the velocity information provided by the 8183-8194
Angstrom Na I absorption doublet, we locate the absorption at the expected
donor velocity of IY UMa.Comment: 5 pages, 4 figures, accepted for publication in MNRA
Combined Chlorophyll Fluorescence and Transcriptomic Analysis Identifies the P3/P4 Transition as a Key stage in Rice Leaf Photosynthetic Development
Leaves are derived from heterotrophic meristem tissue that, at some point, must make the transition to autotrophy via the initiation of photosynthesis. However, the timing and spatial coordination of the molecular and cellular processes underpinning this switch are poorly characterized. Here, we report on the identification of a specific stage in rice (Oryza sativa) leaf development (P3/P4 transition) when photosynthetic competence is first established. Using a combined physiological and molecular approach, we show that elements of stomatal and vascular differentiation are coordinated with the onset of measurable light absorption for photosynthesis. Moreover, by exploring the response of the system to environmental perturbation, we show that the earliest stages of rice leaf development have significant plasticity with respect to elements of cellular differentiation of relevance for mature leaf photosynthetic performance. Finally, by performing an RNA sequencing analysis targeted at the early stages of rice leaf development, we uncover a palette of genes whose expression likely underpins the acquisition of photosynthetic capability. Our results identify the P3/P4 transition as a highly dynamic stage in rice leaf development when several processes for the initiation of photosynthetic competence are coordinated. As well as identifying gene targets for future manipulation of rice leaf structure/function, our data highlight a developmental window during which such manipulations are likely to be most effective
Foundations of character: methodological aspects of a study of character development in three- to six-year-old children with a focus on sharing behaviours
This article focuses on methodological issues arising in a study of character development, using illustrations of âsharing behaviours.â Based primarily in six early years settings in southeast England the research records naturalistic observations of peer interactions for 55 children aged three to six years. Applying grounded theory to the processes of observing, analysing and interpreting evidence required a cautious and collectively reflective approach. The methodology sought to moderate the influence of the researchers' prior knowledge of âgrand theoriesâ of moral development and assumptions about relevance to the observation records. The study's originality lay in the exploration of moral development without reference to any particular grand theory as an explanatory framework; and in the reluctance to be drawn to potentially simplistic rationalisations of the children's intentions on the basis of their observed behaviours. Exploring young children's subjective experiences, this research provides insights into the intricacy of this process, steering away from âneatâ findings and attempting to reflect the sophistication of the children's skilful and sometimes surprising negotiations of moral dilemmas. Implications for practice relate to the complexities involved in attempts to unravel the developing moral characters of young children and the practice through which this may be nurtured
A model of superoutbursts in binaries of SU UMa type
A new mechanism explaining superoutbursts in binaries of SU UMa type is
proposed. In the framework of this mechanism the accretion rate increase
leading to the superoutburst is associated with formation of a spiral wave of a
new "precessional" type in inner gasdynamically unperturbed parts of the
accretion disc. The possibility of existence of this type of waves was
suggested in our previous work (astro-ph/0403053). The features of the
"precessional" spiral wave allow explaining both the energy release during the
outburst and all its observational manifestations. The distinctive
characteristic of a superoutburst in a SU UMa type star is the appearance of
the superhump on the light curve. The proposed model reproduces well the
formation of the superhump as well as its observational features, such as the
period that is 3-7% longer than the orbital one and the detectability of
superhumps regardless of the binary inclination.Comment: LaTeX, 20 pages, 4 figures, to be published in Astron. Z
Low cost circulatory pressure acquisition and fluid infusion rate measurement system for clinical research
Acquiring patient physiological waveforms is useful for studying hemodynamic management and developing medical monitoring systems. A low cost, Arduino controlled data acquisition system acquires arterial pressure waveforms (Edwards Lifesciences TruWave compatible) and measures fluid infusion rate using hanging scales. This system can be used at the same time as a clinical monitor, enabling recording of patient arterial pressure and fluid delivery for clinical research. The system is powered via a USB connection, which additionally provides serial output, aiding compatibility and customisation. A simple software user interface, developed in Python, shows outputs. Each data acquisition system, including all necessary connection cables costs ÌUS$90 and is multiple-use
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