900 research outputs found
PADAMOT : project overview report
Background and relevance to radioactive waste management
International consensus confirms that placing radioactive wastes and spent nuclear fuel deep
underground in a geological repository is the generally preferred option for their long-term
management and disposal. This strategy provides a number of advantages compared to leaving it
on or near the Earth’s surface. These advantages come about because, for a well chosen site, the
geosphere can provide:
• a physical barrier that can negate or buffer against the effects of surface dominated natural
disruptive processes such as deep weathering, glaciation, river and marine erosion or
flooding, asteroid/comet impact and earthquake shaking etc.
• long and slow groundwater return pathways from the facility to the biosphere along which
retardation, dilution and dispersion processes may operate to reduce radionuclide
concentration in the groundwater.
• a stable, and benign geochemical environment to maximise the longevity of the engineered
barriers such as the waste containers and backfill in the facility.
• a natural radiation shield around the wastes.
• a mechanically stable environment in which the facility can be constructed and will
afterwards be protected.
• an environment which reduces the likelihood of the repository being disturbed by inadvertent
human intrusion such as land use changes, construction projects, drilling, quarrying and
mining etc.
• protection against the effects of deliberate human activities such as vandalism, terrorism and
war etc.
However, safety considerations for storing and disposing of long-lived radioactive wastes must
take into account various scenarios that might affect the ability of the geosphere to provide the
functionality listed above. Therefore, in order to provide confidence in the ability of a repository
to perform within the deep geological setting at a particular site, a demonstration of geosphere
“stability” needs to be made. Stability is defined here to be the capacity of a geological and
hydrogeological system to minimise the impact of external influences on the repository
environment, or at least to account for them in a manner that would allow their impacts to be
evaluated and accounted for in any safety assessments.
A repository should be sited where the deep geosphere is a stable host in which the engineered
containment can continue to perform according to design and in which the surrounding
hydrogeological, geomechanical and geochemical environment will continue to operate as a
natural barrier to radionuclide movement towards the biosphere. However, over the long periods
of time during which long-lived radioactive wastes will pose a hazard, environmental change at
the surface has the potential to disrupt the stability of the geosphere and therefore the causes of
environmental change and their potential consequences need to be evaluated.
As noted above, environmental change can include processes such as deep weathering,
glaciation, river and marine erosion. It can also lead to changes in groundwater boundary
conditions through alternating recharge/discharge relationships. One of the key drivers for
environmental change is climate variability. The question then arises, how can geosphere stability be assessed with respect to changes in climate? Key issues raised in connection with
this are:
• What evidence is there that 'going underground' eliminates the extreme conditions that
storage on the surface would be subjected to in the long term?
• How can the additional stability and safety of the deep geosphere be demonstrated with
evidence from the natural system?
As a corollary to this, the capacity of repository sites deep underground in stable rock masses to
mitigate potential impacts of future climate change on groundwater conditions therefore needs to
be tested and demonstrated. To date, generic scenarios for groundwater evolution relating to
climate change are currently weakly constrained by data and process understanding. Hence, the
possibility of site-specific changes of groundwater conditions in the future can only be assessed
and demonstrated by studying groundwater evolution in the past. Stability of groundwater
conditions in the past is an indication of future stability, though both the climatic and geological
contexts must be taken into account in making such an assertion
Mission description and in-flight operations of ERBE instruments on ERBS, NOAA 9, and NOAA 10 spacecraft
Instruments of the Earth Radiation Budget Experiment (ERBE) are operating on three different Earth-orbiting spacecraft. The Earth Radiation Budget Satellite (ERBS) is operated by NASA, and NOAA 9 and NOAA 10 weather satellites are operated by the National Oceanic and Atmospheric Administration (NOAA). This paper is the second in a series that describes the ERBE mission, and data processing and validation procedures. This paper describes the spacecraft and instrument operations for the second full year of in-orbit operations, which extend from February 1986 through January 1987. Validation and archival of radiation measurements made by ERBE instruments during this second year of operation were completed in July 1991. This period includes the only time, November 1986 through January 1987, during which all ERBE instruments aboard the ERBE, NOAA 9, and NOAA 10 spacecraft were simultaneously operational. This paper covers normal and special operations of the spacecraft and instruments, operational anomalies, and the responses of the instruments to in-orbit and seasonal variations in the solar environment
The evolution of Runx genes II. The C-terminal Groucho recruitment motif is present in both eumetazoans and homoscleromorphs but absent in a haplosclerid demosponge
Background. The Runt DNA binding domain (Runx) defines a metazoan family of sequence-specific transcription factors with essential roles in animal ontogeny and stem cell based development. Depending on cis-regulatory context, Runx proteins mediate either transcriptional activation or repression. In many contexts Runx-mediated repression is carried out by Groucho/TLE, recruited to the transcriptional complex via a C-terminal WRPY sequence motif that is found encoded in all heretofore known Runx genes. Findings. Full-length Runx genes were identified in the recently sequenced genomes of phylogenetically diverse metazoans, including placozoans and sponges, the most basally branching members of that clade. No sequences with significant similarity to the Runt domain were found in the genome of the choanoflagellate Monosiga brevicollis, confirming that Runx is a metazoan apomorphy. A contig assembled from genomic sequences of the haplosclerid demosponge Amphimedon queenslandica was used to construct a model of the single Runx gene from that species, AmqRunx, the veracity of which was confirmed by expressed sequences. The encoded sequence of the Runx protein OscRunx from the homoscleromorph sponge Oscarella carmella was also obtained from assembled ESTs. Remarkably, a syntenic linkage between Runx and Supt3h, previously reported in vertebrates, is conserved in A. queenslandica. Whereas OscRunx encodes a C-terminal Groucho-recruitment motif, AmqRunx does not, although a Groucho homologue is found in the A. queenslandica genome. Conclusion. Our results are consistent with the hypothesis that sponges are paraphyletic, and suggest that Runx-WRPY mediated recruitment of Groucho to cis-regulatory sequences originated in the ancestors of eumetazoans following their divergence from demosponges
Factors Associated with the Diversification of the Gut Microbial Communities within Chimpanzees from Gombe National Park.
The gastrointestinal tract harbors large and diverse populations of bacteria that vary among individuals and within individuals over time. Numerous internal and external factors can influence the contents of these microbial communities, including diet, geography, physiology, and the extent of contact among hosts. To investigate the contributions of such factors to the variation and changes in gut microbial communities, we analyzed the distal gut microbiota of individual chimpanzees from two communities in Gombe National Park, Tanzania. These samples, which were derived from 35 chimpanzees, many of whom have been monitored for multiple years, provide an unusually comprehensive longitudinal depth for individuals of known genetic relationships. Although the composition of the great-ape microbiota has been shown to codiversify with host species, indicating that host genetics and phylogeny have played a major role in its differentiation over evolutionary timescales, the geneaological relationships of individual chimpanzees did not coincide with the similarity in their gut microbial communities. However, the inhabitants from adjacent chimpanzee communities could be distinguished based on the contents of their gut microbiota. Despite the broad similarity of community members, as would be expected from shared diet or interactions, long-term immigrants to a community often harbored the most distinctive gut microbiota, suggesting that individuals retain hallmarks of their previous gut microbial communities for extended periods. This pattern was reinforced in several chimpanzees sampled over long temporal scales, in which the major constituents of the gut microbiota were maintained for nearly a decade
Metastatic extrapleural malignant solitary fibrous tumor presenting with hypoglycemia (Doege–Potter syndrome)
AbstractWe report a rare case of metastatic malignant solitary fibrous tumor (SFT) that presented with hypoglycemia because of insulin growth factor-2 production. Initial workup included computed tomography imaging that revealed a large, partially necrotic liver mass, a hypervascular pancreatic head lesion, and 2 renal lesions. Following hepatic resection, pancreatic head resection and nephrectomy, all these lesions demonstrated pathological findings that were consistent with SFT. The patient also had a history of an intracranial mass that had been previously resected and treated with gamma knife therapy at an outside institution, which was found to also be SFT. Six months after initial pancreatic head resection, the patient developed a new lesion involving the pancreatic tail that was found to represent recurrent metastatic SFT. This case emphasizes the highly aggressive nature of extrapleural SFT, while rare, and the role of imaging in follow-up for disease recurrence
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Uncommon Sense, Uncommon Courage: How the New York City School System, Its Teachers, Leadership and Students Responded to the Terror of September 11
Eight public schools are situated within a quarter mile of Ground Zero with 9,000 students ranging in ages from three to eighteen years – grammar, middle and high schools. On Tuesday, September 11, 2001 in the midst of chaos and a relentless unfolding of tragedy, professionals of the Board of Education safely evacuated all 9,000 students without injury. They also ensured that all 1.1 million school children, in every part of the city got home safely, reunited with family and loved ones. They did this as transportation around the City was halted, subways, roads, bridges were closed, and airspace over the United States was shutdown except to military flights. This report is the articulation of a truly effective reaction by a complex organization. Some would label it as luck or extraordinary good fortune. In fact, when all the evidence is finally in, this report argues that the Board of Education’s handling of the crisis presented by 9/11, comprised its “shining moment” – where leadership and courage were manifest and where the paramount objective “get our kids home safe” made the difference between life and death
Bayesian Inference of Species Trees from Multilocus Data
Until recently, it has been common practice for a phylogenetic analysis to use a single gene sequence from a single individual organism as a proxy for an entire species. With technological advances, it is now becoming more common to collect data sets containing multiple gene loci and multiple individuals per species. These data sets often reveal the need to directly model intraspecies polymorphism and incomplete lineage sorting in phylogenetic estimation procedures
Iodoarene-Catalyzed Cyclizations of Unsaturated Amides
The cyclization of N-alkenylamides catalyzed by iodoarenes under oxidative conditions is presented. Five-, six-, and seven-membered rings with a range of substitutions can be prepared by this route. Preliminary data from the use of chiral iodoarenes as precatalysts show that enantiocontrol is feasible
Effect of pay for performance on the management and outcomes of hypertension in the United Kingdom: interrupted time series study
Objective To assess the impact of a pay for performance incentive on quality of care and outcomes among UK patients with hypertension in primary care
Advancing Tests of Relativistic Gravity via Laser Ranging to Phobos
Phobos Laser Ranging (PLR) is a concept for a space mission designed to
advance tests of relativistic gravity in the solar system. PLR's primary
objective is to measure the curvature of space around the Sun, represented by
the Eddington parameter , with an accuracy of two parts in ,
thereby improving today's best result by two orders of magnitude. Other mission
goals include measurements of the time-rate-of-change of the gravitational
constant, and of the gravitational inverse square law at 1.5 AU
distances--with up to two orders-of-magnitude improvement for each. The science
parameters will be estimated using laser ranging measurements of the distance
between an Earth station and an active laser transponder on Phobos capable of
reaching mm-level range resolution. A transponder on Phobos sending 0.25 mJ, 10
ps pulses at 1 kHz, and receiving asynchronous 1 kHz pulses from earth via a 12
cm aperture will permit links that even at maximum range will exceed a photon
per second. A total measurement precision of 50 ps demands a few hundred
photons to average to 1 mm (3.3 ps) range precision. Existing satellite laser
ranging (SLR) facilities--with appropriate augmentation--may be able to
participate in PLR. Since Phobos' orbital period is about 8 hours, each
observatory is guaranteed visibility of the Phobos instrument every Earth day.
Given the current technology readiness level, PLR could be started in 2011 for
launch in 2016 for 3 years of science operations. We discuss the PLR's science
objectives, instrument, and mission design. We also present the details of
science simulations performed to support the mission's primary objectives.Comment: 25 pages, 10 figures, 9 table
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