1,335 research outputs found
The effects of high density plantings of green beans on growth response, yields, quality, and eonomic returns in the Missouri River Valley of western Iowa
Typescript (photocopy) Thesis (M.S.)--Iowa State University, 1975. Includes bibliography
A Descriptive Study of the Reproductive Biology of the Veined Rapa Whelk (Rapana venosa) in the Chesapeake Bay
Investigation of the fundamental constants stability based on the reactor Oklo burn-up analysis
The burn-up for SC56-1472 sample of the natural Oklo reactor zone 3 was
calculated using the modern Monte Carlo codes. We reconstructed the neutron
spectrum in the core by means of the isotope ratios: Sm/Sm and
Lu/Lu. These ratios unambiguously determine the spectrum index
and core temperature. The effective neutron absorption cross section of
Sm calculated using this spectrum was compared with experimental one.
The disagreement between these two values allows to limit a possible shift of
the low laying resonance of Sm even more . Then, these limits were
converted to the limits for the change of the fine structure constant .
We found that for the rate of change the inequality is fulfilled, which is of the next
higher order than our previous limit.Comment: 16 pages, 7 figure
Temperature-sensitive polymer-nanoshell composites for photothermally modulated drug delivery
General Surgery in crisis - the critical shortage
Introduction: General surgery is facing a serious crisis. There has been a significant decline in the number of applicants for registrar posts and an inability to attract and retain general surgical specialists in the state sector. The Association of Surgeons of South Africa (ASA) undertook this study to determine the extent and cause of the problem. Methods: The study involved a combination of desk research and structured interviews. In addition, the Health Professions Council of South Africa (HPCSA) database was reviewed and compared with the South African Medical Association (SAMA) and ASA databases. The medical schools provided information about student numbers and demographics, and the National Department of Health provided information about the status of medical practitioner and specialist posts in the state sector. Results: Overall, 26.1% of the specialist posts were vacant. The situation was particularly critical in Mpumalanga and the Eastern Cape, where 84% and 58% of the specialist posts were vacant. Using a predictive model, a conservative estimate of the need for general surgeons was found to be at least 50 per year. Currently the eight medical schools graduate about 25 general surgeons per year. The changing demographics of medical students may be partly responsible for the decline in registrar applicants. Conclusion. The findings from this study have revealed that the shortage of general surgeons in the state sector has reached critical levels
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Hexokinase is necessary for glucose-mediated photosynthesis repression and lipid accumulation in a green alga.
Global primary production is driven largely by oxygenic photosynthesis, with algae as major contributors. The green alga Chromochloris zofingiensis reversibly switches off photosynthesis in the presence of glucose in the light and augments production of biofuel precursors (triacylglycerols) and the high-value antioxidant astaxanthin. Here we used forward genetics to reveal that this photosynthetic and metabolic switch is mediated by the glycolytic enzyme hexokinase (CzHXK1). In contrast to wild-type, glucose-treated hxk1 mutants do not shut off photosynthesis or accumulate astaxanthin, triacylglycerols, or cytoplasmic lipid droplets. We show that CzHXK1 is critical for the regulation of genes related to photosynthesis, ketocarotenoid synthesis and fatty acid biosynthesis. Sugars play fundamental regulatory roles in gene expression, physiology, metabolism, and growth in plants and animals, and we introduce a relatively simple, emerging model system to investigate conserved eukaryotic sugar sensing and signaling at the base of the green lineage
Movement patterns of Pacific crown-of-thorns starfish (Acanthaster cf. solaris) linked to habitat structure and prey availability
Patterns of movement and habitat use by adult crown-of-thorns starfishes (Acanthaster spp.)
will have a major bearing on their distribution, reproductive capacity, and impacts on coral
assemblages and reef ecosystems. The spatial and temporal scales over which crown-ofthorns starfish move will also have important implications for the scales at which they will be
most effectively managed. Movement patterns of crown-of-thorns starfish have been studied
previously, though mostly over small distances (metres) and limited timeframes (minutes to
hours). This study reports on explicit studies that measured the movement rates and
movement patterns of Pacific crown-of-thorns starfish (Acanthaster cf. solaris) at a range of
temporal and spatial scales. In the first instance, we measured the instantaneous movement
rates of starfish (n = 218) across different substrates; sand, coral rubble and consolidated
carbonate pavement. This study was conducted in a large (5m diameter) tank, using video
recordings that were then analysed to determine the mean and maximum rates of movement
over successive 15-second intervals.
To assess movement patterns of A. cf. solaris in the field, short-term tagging and movement
studies were undertaken at Rib Reef, in the central GBR. All starfish (n = 357) recorded on
semi-permanent transects were individually tagged using numbered pieces of flagging tape.
The precise position of each starfish (where detected) was then recorded during successive
surveys during day and night for up to 4 days. To further scale-up movement studies for crownof-thorns starfish we tagged 50 crown-of-thorns starfish using V7 (69KHZ) acoustic
transmitters, at Lodestone Reef or Big Broadhurst Reef. The position of these starfish relative
to acoustic receivers deployed 50-200m along the edge of the reef was recorded (at 3-minute
intervals) for up to 8 months. Passive acoustic monitoring was intended to provide greater
insights into longer-term (weeks to months) and larger-scale (kilometres) patterns of
movement for crown-of-thorns starfish, but provided much less resolution regarding fine-scale
movements of individual starfish.
Instantaneous measures of movement capacity for A. cf. solaris (in aquaria) showed that these
starfish are capable of moving at 20-35 cm per minute, and move fastest over sand. Despite
their capacity for movement, field-based studies suggested that crown-of-thorns starfish
actually move very little at scales of days to weeks, and even months. For starfish that were
tagged with temporary visual markers, the minimum displacement distance recorded for the
majority of starfish (88.0%) was <2m throughout the course of the study. Moreover, starfish
that did move to feed (mostly at night) often returned to the same resting location between
feeding bouts. Similarly, starfish tagged with acoustic transmitters for up to 6 months were only
ever detected on adjacent receivers with large overlap in their ranges, suggesting that all
starfish remained within 50-100m of where they were initially found and tagged for up to 6-
months. The frequency and duration of passive detections varied greatly among individual
starfish tagged with transmitters, with detections peaking in early hours of the morning.
While this study shows that it is possible to effectively tag crown-of-thorns starfish, both over
short and longer time-frames, there were considerable logistical challenges to documenting
occasional large-scale, and presumably quite rapid, displacement of individual starfish. It is
clear that crown-of-thorns starfish generally move very little and remain within localised areas
(even returning to the same sheltering location between successive feeding bouts) of moderate to high coral cover. However, Acanthaster spp. are also capable of moving large distances
when necessary, presumably when coral prey are locally depleted. It will be important to
understand the nature and scale of both modes of movement to effectively manage population
irruptions of crown-of-thorns starfish. Documenting the incidence and rates of movement
during these infrequent events remains a priority for future research
Modelling the costs and benefits of hybrid buses from a whole-life perspective
Hybrid electric-diesel engine technologies offer the potential to reduce fuel consumption in buses by around 40%. These savings
can largely be attributed to regenerative braking – the ability to store in a battery energy that would otherwise have been lost
under braking. Lower fuel consumption makes sense economically for bus operators through reduced running costs; hybrid
engines have other wider benefits, though, such as reducing emissions and noise, and providing smoother acceleration and
braking. The costs associated with hybrid technologies are significant, however, with hybrid vehicles currently costing around
50% more to buy than conventional buses.
With Alexander Dennis and BAE Systems, UCL is conducting a three-year systems engineering research and development
project to adapt and optimise hybrid buses for the UK and European market. This paper investigates one aspect of this project –
the costs and benefits of introducing hybrid bus technologies from a whole-life perspective. We find that fuel and emissions
savings alone do not provide a compelling case for hybrid buses based on current prices. However, as the cost of fuel rises, and
when the social and environmental impacts of motor vehicle use are better accounted for, hybrid technology outperforms
conventional diesel technology
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