4,453 research outputs found
Effects of beet western yellows virus on growth and yield of oilseed rape (Brassica napus )
Field trials were undertaken in Suffolk in commercial crops of autumn-sown oilseed rape cv.
Capricorn during 1993/94, cv. Apex in 1994/95. Plots were artificially infected with beet western
yellows virus (BWYV) using viruliferous Myzus persicae, giving 73 to 94% infection. Control plots
had natural infection ranging from 0 to 17·8%. Destructive plant samples were taken from each of
the infected and control plots throughout the seasons for growth analyses, and final yields were
measured on 44 m2 areas combine harvested from each plot. The seed yields of infected plots were
26 and 11% lower than control plots in 1994 and 1995 respectively (P<0·001).Harvested seed yields were shown to be inversely proportional to the area of the plot that was
inoculated with BWYV. Infection significantly lowered the oil content in 1995 from 47·9 to 46·8%
(P<0·001), and increased glucosinolate levels from 16·12 to 18·37 μmol/g (P<0·01). BWYV caused
a significant reduction in plant height and in numbers of primary branches in the 1993/94 trial and
had an effect on the dry weight of the leaves, stalks, racemes and pods at some sample dates in both
seasons. Virus-testing of infected plants showed that BWYV was present in the pod wall, the septum
and seed coat; two of 78 embryo samples also contained virus. It was concluded that BWYV can
cause significant yield losses in those years in which there is a high incidence of virus in the
overwintered crops.</jats:p
Water Tank with Capillary Air/Liquid Separation
A bladderless water tank (see figure) has been developed that contains capillary devices that allow it to be filled and emptied, as needed, in microgravity. When filled with water, the tank shields human occupants of a spacecraft against cosmic radiation. A membrane that is permeable by air but is hydrophobic (neither wettable nor permeable by liquid water) covers one inside surface of the tank. Grooves between the surface and the membrane allow air to flow through vent holes in the surface as the tank is filled or drained. A margin of wettable surface surrounds the edges of the membrane, and all the other inside tank surfaces are also wettable. A fill/drain port is located in one corner of the tank and is covered with a hydrophilic membrane. As filling begins, water runs from the hydrophilic membrane into the corner fillets of the tank walls. Continued filling in the absence of gravity will result in a single contiguous air bubble that will be vented through the hydrophobic membrane. The bubble will be reduced in size until it becomes spherical and smaller than the tank thickness. Draining the tank reverses the process. Air is introduced through the hydrophobic membrane, and liquid continuity is maintained with the fill/drain port through the corner fillets. Even after the tank is emptied, as long as the suction pressure on the hydrophilic membrane does not exceed its bubble point, no air will be drawn into the liquid line
Off-World Mental Health:Considerations for the Design of Well-being-Supportive Technologies for Deep Space Exploration
During future long-duration space exploration missions, humans will be exposed to combinations of extreme physical, psychological, and interpersonal demands. These demands create risks for the safety, performance, health, and well-being of both individuals and crew. The communication latency in deep space means that explorers will increasingly have to operate independently and take responsibility for their own self-care and self-management. At present, several research programs are focused on developing and testing digital technologies and countermeasures that support the effective functioning of deep space crews. Although promising, these initiatives have been stimulated mostly by technological opportunity rather than cogent theory. In this perspective, we argue that digital technologies developed for spaceflight should be informed by well-being–supportive design principles and be cognizant of broader conversations around the development and use of digital health applications, especially pertaining to issues of autonomy, privacy, and trust. These issues are important for designing potentially mission-critical health technologies and may be determining factors in the safe and successful completion of future off-world endeavors.publishedVersio
LEGUS Discovery of a Light Echo Around Supernova 2012aw
We have discovered a luminous light echo around the normal Type II-Plateau
Supernova (SN) 2012aw in Messier 95 (M95; NGC 3351), detected in images
obtained approximately two years after explosion with the Wide Field Channel 3
on-board the Hubble Space Telescope (HST) by the Legacy ExtraGalactic
Ultraviolet Survey (LEGUS). The multi-band observations span from the
near-ultraviolet through the optical (F275W, F336W, F438W, F555W, and F814W).
The apparent brightness of the echo at the time was ~21--22 mag in all of these
bands. The echo appears circular, although less obviously as a ring, with an
inhomogeneous surface brightness, in particular, a prominent enhanced
brightness to the southeast. The SN itself was still detectable, particularly
in the redder bands. We are able to model the light echo as the time-integrated
SN light scattered off of diffuse interstellar dust in the SN environment. We
have assumed that this dust is analogous to that in the Milky Way with R_V=3.1.
The SN light curves that we consider also include models of the unobserved
early burst of light from the SN shock breakout. Our analysis of the echo
suggests that the distance from the SN to the scattering dust elements along
the echo is ~45 pc. The implied visual extinction for the echo-producing dust
is consistent with estimates made previously from the SN itself. Finally, our
estimate of the SN brightness in F814W is fainter than that measured for the
red supergiant star at the precise SN location in pre-SN images, possibly
indicating that the star has vanished and confirming it as the likely SN
progenitor.Comment: 10 pages, 9 figures, to appear in the Astrophysical Journa
Vitamin C Prevents Hypogonadal Bone Loss
Epidemiologic studies correlate low vitamin C intake with bone loss. The genetic deletion of enzymes involved in de novo vitamin C synthesis in mice, likewise, causes severe osteoporosis. However, very few studies have evaluated a protective role of this dietary supplement on the skeleton. Here, we show that the ingestion of vitamin C prevents the low-turnover bone loss following ovariectomy in mice. We show that this prevention in areal bone mineral density and micro-CT parameters results from the stimulation of bone formation, demonstrable in vivo by histomorphometry, bone marker measurements, and quantitative PCR. Notably, the reductions in the bone formation rate, plasma osteocalcin levels, and ex vivo osteoblast gene expression 8 weeks post-ovariectomy are all returned to levels of sham-operated controls. The study establishes vitamin C as a skeletal anabolic agent. © 2012 Zhu et al
Advancing national greenhouse gas inventories for agriculture in developing countries : improving activity data, emission factors and software technology
Peer reviewedPublisher PD
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